docs: add rack state history docs for nico-cli

[sydneyl-nvidia]

How would you describe the priority of this documentation request

Medium

Describe the future/missing documentation

This needs documenting:

Show state history for a rack:
    $ nico-admin-cli rack state-history ...

Fix will be a new page called rack-state-history.md, at the same level as docs/manuals/nico-admin-cli/commands/rack/rack-profile-show.md and its friends

Code of Conduct

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• I have searched the open documentation issues and have found no duplicates for this documentation issue