remote command docs

[thorinaboenke]

Improved the remote command documentation in attackmate.

• Added a seealso link to remote_config,
• added a Context and State section explaining playbook vs command statefulness, created a corresponding two-page drawio diagram, embedded pngs in the remote.rst docs
• added a note in remote.rst and remote_config.rst referencing the API server repo and Ansible role.
• fixed some warnings on building html