Reorganise mypy_self_check.ini (#20515)

mypy_self_check.ini

diff --git a/mypy_self_check.ini b/mypy_self_check.ini
index 81a8614..cec47fb 100644
--- a/mypy_self_check.ini
+++ b/mypy_self_check.ini
@@ -1,17 +1,25 @@
 [mypy]
 
-strict = True
-local_partial_types = True
-disallow_any_unimported = True
-show_traceback = True
-pretty = True
-always_false = MYPYC
-plugins = mypy.plugins.proper_plugin
 python_version = 3.10
 exclude = mypy/typeshed/|mypyc/test-data/|mypyc/lib-rt/
+
+# Options that affect type checking
+strict = True
+allow_redefinition_new = True
+local_partial_types = True
+disallow_any_unimported = True
+warn_unreachable = True
 enable_error_code = ignore-without-code,redundant-expr
 enable_incomplete_feature = PreciseTupleTypes
+
+# Plugins or custom behaviour
+always_false = MYPYC
+plugins = mypy.plugins.proper_plugin
+
+# Options that affect output
+pretty = True
 show_error_code_links = True
-warn_unreachable = True
+show_traceback = True
+
+# Miscellaneous
 sqlite_cache = True
-allow_redefinition_new = True