Note that Python 3.7 support is limited (#10601)

README.md

@@ -20,7 +20,9 @@ the project the stubs are for, but instead report them here to typeshed.**
 Further documentation on stub files, typeshed, and Python's typing system in
 general, can also be found at https://typing.readthedocs.io/en/latest/.
 
-Typeshed supports Python versions 3.7 and up.
+Typeshed fully supports Python versions 3.8 and up. Support for Python 3.7
+is limited: see https://github.com/python/typeshed/issues/10113
+for details.
 
 ## Using