Add some guides

[felixfontein]

SUMMARY

Using ansible-community/antsibull#255, adds two guides that describe how to create self-signed certificates, and how to set up and use an ownca.

You can see the result of this PR here: https://ansible.fontein.de/collections/community/crypto/#scenario-guides (assuming that the antsibull PR is merged)

Fixes #226.

ISSUE TYPE

• Docs Pull Request

COMPONENT NAME

scenario guides

[felixfontein]

Since ansible-community/antsibull#255 has been merged, this is no longer a WIP 🎉

[Ajpantuso]

LGTM.

On a side note I see sanity ran these through rstcheck, but are there any content guidelines for scenario guides? (To keep submitters and reviewers on the same page)

[felixfontein]

Not really, this is still too new ;-) Well, there's antsibull-lint which should pass on the files. (I'll add that to CI soon.) (It checks whether the labels have the correct form, and also runs rstcheck.)

[felixfontein]

The check successfully failed with:

00:16 Test "extra-docs" failed with the following 1 errors:
00:16 ./docs/docsite/rst/guide_selfsigned.rst:1:0: Label "ansible_collecions.community.crypto.docsite.guide_selfsigned" does not start with expected prefix "ansible_collections.community.crypto.docsite."

[felixfontein]

@Ajpantuso thanks for reviewing the docs :)