bpo-35766: Merge typed_ast back into CPython (GH-11645)

diff --git a/Doc/library/token.rst b/Doc/library/token.rst
index 5358eb5..4936e9a 100644
--- a/Doc/library/token.rst
+++ b/Doc/library/token.rst
@@ -69,6 +69,13 @@
    always be an ``ENCODING`` token.
 
 
+.. data:: TYPE_COMMENT
+
+   Token value indicating that a type comment was recognized.  Such
+   tokens are only produced when :func:`ast.parse()` is invoked with
+   ``type_comments=True``.
+
+
 .. versionchanged:: 3.5
    Added :data:`AWAIT` and :data:`ASYNC` tokens.
 
@@ -78,3 +85,6 @@
 .. versionchanged:: 3.7
    Removed :data:`AWAIT` and :data:`ASYNC` tokens. "async" and "await" are
    now tokenized as :data:`NAME` tokens.
+
+.. versionchanged:: 3.8
+   Added :data:`TYPE_COMMENT`.