Fixes documentation role

The docs service was not working because Ansible tried to include a role docs which does not exist (but homelabos_docs does).

In order to avoid the renaming of the config and keep the homelabs_ prefix in place, this MR adds a docs role that just includes homelabos_docs. Kind of an alias.

More solutions could be thought of, but this implementation has the double benefits of fixing the current docs service while maintaining backward compatibility in terms of naming, config etc.