Incorporate 'shared snippets' for the collection docs into the main rst files

[samccann]

Back in the dim dawn of time, we had repeated content in the Galaxy guides and the collection guides, so I added a bunch of collection snippets in the shared snippets folder:
https://github.com/ansible/ansible-documentation/tree/devel/docs/docsite/rst/shared_snippets

This issue is to review them and replace them with direct content in the main rst files where they are linked to now if they are only used in one location.

So basically:

• grep to see where they are used. Ignore any .po files (translation files)
• If a snippet is only used in one location, copy the content there and remove the snippet.
• If a snippet is used in more than one location, add a comment here and we can as a group decide what to do.

[samccann]

See #1315 for an example that did this for one of the snippets.