add '_facts' rule to module checklist (#53359)

* add '_facts' rule to module checklist

* Update docs/docsite/rst/dev_guide/developing_modules_checklist.rst

Co-Authored-By: bcoca <bcoca@users.noreply.github.com>

docs/docsite/rst/dev_guide/developing_modules_checklist.rst

@@ -24,6 +24,7 @@ To contribute a module to Ansible, you must:
 * minimize module dependencies
 * support :ref:`check_mode <check_mode_dry>` if possible
 * ensure your code is readable
+* if a module is named `<something>_facts`, it is because it is returning `ansible_facts`. Do not name modules that do not do this with `_facts`.
 
 Please make sure your module meets these requirements before you submit your PR/proposal. If you have questions, reach out via `Ansible's IRC chat channel <http://irc.freenode.net>`_ or the `Ansible development mailing list <https://groups.google.com/group/ansible-devel>`_.