Shorten README, link to docs page (#169)

diff --git a/README.md b/README.md
index aad814e..ddc1188 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,9 @@
 
 [![Chat at https://gitter.im/python/typing](https://badges.gitter.im/python/typing.svg)](https://gitter.im/python/typing)
 
+[Documentation](https://typing-extensions.readthedocs.io/en/latest/#) –
+[PyPI](https://pypi.org/project/typing-extensions/)
+
 ## Overview
 
 The `typing_extensions` module serves two related purposes:
@@ -12,200 +15,21 @@
 - Enable experimentation with new type system PEPs before they are accepted and
   added to the `typing` module.
 
-New features may be added to `typing_extensions` as soon as they are specified
-in a PEP that has been added to the [python/peps](https://github.com/python/peps)
-repository. If the PEP is accepted, the feature will then be added to `typing`
-for the next CPython release. No typing PEP has been rejected so far, so we
-haven't yet figured out how to deal with that possibility.
-
-Starting with version 4.0.0, `typing_extensions` uses
+`typing_extensions` uses
 [Semantic Versioning](https://semver.org/). The
-major version is incremented for all backwards-incompatible changes.
+major version will be incremented only for backwards-incompatible changes.
 Therefore, it's safe to depend
 on `typing_extensions` like this: `typing_extensions >=x.y, <(x+1)`,
 where `x.y` is the first version that includes all features you need.
 
-`typing_extensions` supports Python versions 3.7 and higher. In the future,
-support for older Python versions will be dropped some time after that version
-reaches end of life.
+`typing_extensions` supports Python versions 3.7 and higher.
 
 ## Included items
 
-This module currently contains the following:
-
-- Experimental features
-
-  - The `default=` argument to `TypeVar`, `ParamSpec`, and `TypeVarTuple` (see [PEP 696](https://peps.python.org/pep-0696/))
-  - The `infer_variance=` argument to `TypeVar` (see [PEP 695](https://peps.python.org/pep-0695/))
-  - The `@deprecated` decorator (see [PEP 702](https://peps.python.org/pep-0702/))
-
-- In the standard library since Python 3.12
-
-  - `override` (equivalent to `typing.override`; see [PEP 698](https://peps.python.org/pep-0698/))
-  - `TypeAliasType` (equivalent to `typing.TypeAliasType`; see [PEP 695](https://peps.python.org/pep-0695/))
-  - `Buffer` (equivalent to `collections.abc.Buffer`; see [PEP 688](https://peps.python.org/pep-0688/))
-  - `get_original_bases` (equivalent to
-    [`types.get_original_bases`](https://docs.python.org/3.12/library/types.html#types.get_original_bases)
-    on 3.12+).
-
-    This function should always produce correct results when called on classes
-    constructed using features from `typing_extensions`. However, it may
-    produce incorrect results when called on some `NamedTuple` or `TypedDict`
-    classes that use `typing.{NamedTuple,TypedDict}` on Python <=3.11.
-
-- In `typing` since Python 3.11
-
-  - `assert_never`
-  - `assert_type`
-  - `clear_overloads`
-  - `@dataclass_transform()` (see [PEP 681](https://peps.python.org/pep-0681/))
-  - `get_overloads`
-  - `LiteralString` (see [PEP 675](https://peps.python.org/pep-0675/))
-  - `Never`
-  - `NotRequired` (see [PEP 655](https://peps.python.org/pep-0655/))
-  - `reveal_type`
-  - `Required` (see [PEP 655](https://peps.python.org/pep-0655/))
-  - `Self` (see [PEP 673](https://peps.python.org/pep-0673/))
-  - `TypeVarTuple` (see [PEP 646](https://peps.python.org/pep-0646/); the `typing_extensions` version supports the `default=` argument from [PEP 696](https://peps.python.org/pep-0696/))
-  - `Unpack` (see [PEP 646](https://peps.python.org/pep-0646/))
-
-- In `typing` since Python 3.10
-
-  - `Concatenate` (see [PEP 612](https://peps.python.org/pep-0612/))
-  - `ParamSpec` (see [PEP 612](https://peps.python.org/pep-0612/); the `typing_extensions` version supports the `default=` argument from [PEP 696](https://peps.python.org/pep-0696/))
-  - `ParamSpecArgs` (see [PEP 612](https://peps.python.org/pep-0612/))
-  - `ParamSpecKwargs` (see [PEP 612](https://peps.python.org/pep-0612/))
-  - `TypeAlias` (see [PEP 613](https://peps.python.org/pep-0613/))
-  - `TypeGuard` (see [PEP 647](https://peps.python.org/pep-0647/))
-  - `is_typeddict`
-
-- In `typing` since Python 3.9
-
-  - `Annotated` (see [PEP 593](https://peps.python.org/pep-0593/))
-
-- In `typing` since Python 3.8
-
-  - `final` (see [PEP 591](https://peps.python.org/pep-0591/))
-  - `Final` (see [PEP 591](https://peps.python.org/pep-0591/))
-  - `Literal` (see [PEP 586](https://peps.python.org/pep-0586/))
-  - `Protocol` (see [PEP 544](https://peps.python.org/pep-0544/))
-  - `runtime_checkable` (see [PEP 544](https://peps.python.org/pep-0544/))
-  - `TypedDict` (see [PEP 589](https://peps.python.org/pep-0589/))
-  - `get_origin` (`typing_extensions` provides this function only in Python 3.7+)
-  - `get_args` (`typing_extensions` provides this function only in Python 3.7+)
-  - `SupportsIndex`
-
-- In `typing` since Python 3.7
-
-  - `OrderedDict`
-
-- In `typing` since Python 3.5 or 3.6 (see [the typing documentation](https://docs.python.org/3.10/library/typing.html) for details)
-
-  - `AsyncContextManager`
-  - `AsyncGenerator`
-  - `AsyncIterable`
-  - `AsyncIterator`
-  - `Awaitable`
-  - `ChainMap`
-  - `ClassVar` (see [PEP 526](https://peps.python.org/pep-0526/))
-  - `ContextManager`
-  - `Coroutine`
-  - `Counter`
-  - `DefaultDict`
-  - `Deque`
-  - `NewType`
-  - `NoReturn`
-  - `overload`
-  - `Text`
-  - `Type`
-  - `TYPE_CHECKING`
-  - `get_type_hints`
-
-- The following have always been present in `typing`, but the `typing_extensions` versions provide
-  additional features:
-
-  - `Any` (supports inheritance since Python 3.11)
-  - `NamedTuple` (supports multiple inheritance with `Generic` since Python 3.11)
-  - `TypeVar` (see PEPs [695](https://peps.python.org/pep-0695/) and [696](https://peps.python.org/pep-0696/))
-
-The following runtime-checkable protocols have always been present in `typing`,
-but the `isinstance()` checks against the `typing_extensions` versions are much
-faster on Python <3.12:
-
-  - `SupportsInt`
-  - `SupportsFloat`
-  - `SupportsComplex`
-  - `SupportsBytes`
-  - `SupportsAbs`
-  - `SupportsRound`
-
-# Other Notes and Limitations
-
-Certain objects were changed after they were added to `typing`, and
-`typing_extensions` provides a backport even on newer Python versions:
-
-- `TypedDict` does not store runtime information
-  about which (if any) keys are non-required in Python 3.8, and does not
-  honor the `total` keyword with old-style `TypedDict()` in Python
-  3.9.0 and 3.9.1. `TypedDict` also does not support multiple inheritance
-  with `typing.Generic` on Python <3.11, and `TypedDict` classes do not
-  consistently have the `__orig_bases__` attribute on Python <3.12. The
-  `typing_extensions` backport provides all of these features and bugfixes on
-  all Python versions.
-- `get_origin` and `get_args` lack support for `Annotated` in
-  Python 3.8 and lack support for `ParamSpecArgs` and `ParamSpecKwargs`
-  in 3.9.
-- `@final` was changed in Python 3.11 to set the `.__final__` attribute.
-- `@overload` was changed in Python 3.11 to make function overloads
-  introspectable at runtime. In order to access overloads with
-  `typing_extensions.get_overloads()`, you must use
-  `@typing_extensions.overload`.
-- `NamedTuple` was changed in Python 3.11 to allow for multiple inheritance
-  with `typing.Generic`. Call-based `NamedTuple`s were changed in Python 3.12
-  so that they have an `__orig_bases__` attribute, the same as class-based
-  `NamedTuple`s.
-- Since Python 3.11, it has been possible to inherit from `Any` at
-  runtime. `typing_extensions.Any` also provides this capability.
-- `TypeVar` gains two additional parameters, `default=` and `infer_variance=`,
-  in the draft PEPs [695](https://peps.python.org/pep-0695/) and [696](https://peps.python.org/pep-0696/), which are being considered for inclusion
-  in Python 3.12.
-- `Protocol` was added in Python 3.8, but several bugfixes have been made in
-  subsequent releases, as well as significant performance improvements to
-  runtime-checkable protocols in Python 3.12. `typing_extensions` backports the
-  3.12+ version to Python 3.7+.
-- `SupportsInt`, `SupportsFloat`, `SupportsComplex`, `SupportsBytes`,
-  `SupportsAbs` and `SupportsRound` have always been present in the `typing`
-  module. Meanwhile, `SupportsIndex` was added in Python 3.8. However,
-  `isinstance()` checks against all these protocols were sped up significantly
-  on Python 3.12. `typing_extensions` backports the faster versions to Python
-  3.7+.
-- `Literal` does not flatten or deduplicate parameters on Python <3.9.1, and a
-  caching bug was fixed in 3.10.1/3.9.8. The `typing_extensions` version
-  flattens and deduplicates parameters on all Python versions, and the caching
-  bug is also fixed on all versions.
-- `NewType` has been in the `typing` module since Python 3.5.2, but
-  user-defined `NewType`s are only pickleable on Python 3.10+.
-  `typing_extensions.NewType` backports this feature to all Python versions.
-- `Unpack` was added in Python 3.11, but the repr was changed in Python 3.12;
-  `typing_extensions.Unpack` has the newer repr on all versions.
-
-There are a few types whose interface was modified between different
-versions of typing. For example, `typing.Sequence` was modified to
-subclass `typing.Reversible` as of Python 3.5.3.
-
-These changes are _not_ backported to prevent subtle compatibility
-issues when mixing the differing implementations of modified classes.
-
-Certain types have incorrect runtime behavior due to limitations of older
-versions of the typing module:
-
-- `ParamSpec` and `Concatenate` will not work with `get_args` and
-  `get_origin`. Certain [PEP 612](https://peps.python.org/pep-0612/) special cases in user-defined
-  `Generic`s are also not available.
-
-These types are only guaranteed to work for static type checking.
+See [the documentation](https://typing-extensions.readthedocs.io/en/latest/#) for a
+complete listing of module contents.
 
 ## Running tests
 
-To run tests, navigate into the appropriate source directory and run
+To run tests, navigate into the `src/` directory and run
 `test_typing_extensions.py`.
diff --git a/pyproject.toml b/pyproject.toml
index 67d81a1..aec54d3 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -46,7 +46,7 @@
 Home = "https://github.com/python/typing_extensions"
 Repository = "https://github.com/python/typing_extensions"
 Changes = "https://github.com/python/typing_extensions/blob/main/CHANGELOG.md"
-Documentation = "https://typing.readthedocs.io/"
+Documentation = "https://typing-extensions.readthedocs.io/"
 "Bug Tracker" = "https://github.com/python/typing_extensions/issues"
 "Q & A" = "https://github.com/python/typing/discussions"