gh-146636: Add Free-threaded Stable ABI migration guide (GH-150580)

(cherry picked from commit c720e18)

Co-authored-by: Petr Viktorin <encukou@gmail.com>
Co-authored-by: Charlie Lin <tuug@gmx.us>
Co-authored-by: da-woods <dw-git@d-woods.co.uk>
Co-authored-by: Stan Ulbrych <stan@python.org>
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

Author: 5 people

Doc/bugs.rst

@@ -12,6 +12,9 @@ It can be sometimes faster to fix bugs yourself and contribute patches to
 Python as it streamlines the process and involves fewer people. Learn how to
 :ref:`contribute <contributing-to-python>`.
 
+
+.. _reporting-documentation-bugs:
+
 Documentation bugs
 ==================