ansible-core: new module detection has wrong namespace lib.ansible.modules

[felixfontein]

This causes the "New modules" entries to be shown in a category Lib, and then ansible.modules:

• https://github.com/ansible/ansible/blob/stable-2.18/changelogs/CHANGELOG-v2.18.rst#new-modules
• https://github.com/ansible/ansible/blob/stable-2.15/changelogs/CHANGELOG-v2.15.rst#new-modules

In the ansible-core 2.11 changelog this was still working correctly:

• https://github.com/ansible/ansible/blob/stable-2.11/changelogs/CHANGELOG-v2.11.rst#new-modules

My guess is that it's related to #72.

[felixfontein]

CC @mattclay