[docs] [issue43739] Fixing the example code in Doc/extending/extending.rst to declare and initialize the pmodule variable to be of the right type.

Shreyan Avigyan <shreyan.avigyan@gmail.com> added the comment: Please have a review of my change in the documentation. (Note: I have not signed the Python CLA because I think a simple fix in the documentation doesn't require it.) ---------- _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue43739> _______________________________________