Document CLI, Ansible, and API for registering a host

[asteflova]

What changes are you introducing?

I'm describing alternative ways of registering a host: CLI, Ansible, API.

Why are you introducing these changes? (Explanation, links to references, issues, etc.)

https://issues.redhat.com/browse/SAT-28377 requested adding the Hammer command and API resource that correspond to the existing web UI procedure as users weren't aware of their existence and were unable to look them up. Then on top of that, prompted by a conversation with @evgeni, I thought it might be a good idea to add a reference to the corresponding Ansible module too.

Anything else to add? (Considerations, potential downsides, alternative solutions you have explored, etc.)

The CLI, Ansible, and API "procedures" are very minimal by design. Users have very good reference documentation available to them (--help, ansible-doc, and built-in API reference) and I don't want to duplicate it in the guides.

I'm requesting cherry-picks down to 3.7 only because that's what https://github.com/theforeman/foreman-documentation/pull/3143, which targets the same procedure, did.

Checklists

• [x] I am okay with my commits getting squashed when you merge this PR.
• [x] I am familiar with the contributing guidelines.

Please cherry-pick my commits into:

• [x] Foreman 3.12/Katello 4.14 (Satellite 6.16)
• [x] Foreman 3.11/Katello 4.13
• [x] Foreman 3.10/Katello 4.12
• [x] Foreman 3.9/Katello 4.11 (Satellite 6.15; orcharhino 6.8/6.9/6.10)
• [x] Foreman 3.8/Katello 4.10
• [x] Foreman 3.7/Katello 4.9 (Satellite 6.14)
• [ ] Foreman 3.6/Katello 4.8
• [ ] Foreman 3.5/Katello 4.7 (Satellite 6.13; orcharhino 6.6/6.7)
• We do not accept PRs for Foreman older than 3.5.

[github-actions[bot]]

The PR preview for 8942746bf6e9f04887271afd6875b08b76959ffc is available at theforeman-foreman-documentation-preview-pr-3329.surge.sh

The following output files are affected by this PR:

• Managing_Hosts/index-foreman-el.html
• Managing_Hosts/index-katello.html
• Managing_Hosts/index-orcharhino.html
• Managing_Hosts/index-satellite.html
• Provisioning_Hosts/index-satellite.html

show diff

show diff as HTML

[asteflova]

Merged to "master" and cherry-picked:

ab14f726a4..4bede6f080 3.12 -> 3.12 78b3649c58..5bc6dc0d87 3.11 -> 3.11 19ffe82ae7..dd9eb21688 3.10 -> 3.10 9f422ec1b0..ee9d962b71 3.9 -> 3.9 b2c6277a88..8f8e5ea4e5 3.8 -> 3.8 a4f55fb7ca..b584901b73 3.7 -> 3.7