Adding link to source code of any extras module in documentation

For extras modules documentation, we ain’t adding sources of that module currently.

How about adding it with a category: “Source Code: https://github.com/pgolm/ansible-playbook-monit.git” ? Using this, we can easily find the sources of ansible recommended modules.
This avoids ambiguity with other projects available on internet.

All 'extras' modules are in https://github.com/ansible/ansible-modules-extras.