unhide and document "hidden" commands

[tgross]

The operator raft _info, operator raft _logs and operator raft _state, and operator snapshot _state commands are hidden from the CLI output and are undocumented. These commands were intended to be experimental and internal for the Nomad engineering team, but we've found them to be useful for advanced operators in general.

Make all these commands "public" and documented, with warnings in the documentation that they expose Nomad state internals and therefore don't have "stable" interfaces and should be used with caution.

[github-actions]

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