Help: Fix find_package search order w.r.t. globs

Add documentation to clarify that `find_package` searches paths in the
specified order and stops at the first match.  Clarify documentation of
`CMAKE_FIND_PACKAGE_SORT_*` to match the actual behavior.

Note that no behavior is actually changed, this merely improves the
documentation to reflect actual behavior rather than seeming to imply
something else.

Also, update the test to verify that what we claim in the updated
documentation is what's actually happening.
5 files changed