Requirements and doxygen update - Peek/Poke cmds

[dmknutsen]

Checklist (Please check before submitting)

• [ x] I reviewed the Contributing Guide.
• [x ] I reviewed the README file to see if the feature is in the major future work.
• [x ] I performed a cursory search to see if the feature request is relevant, not redundant, nor in conflict with other tickets.

Is your feature request related to a problem? Please describe.
When a peek or poke is performed, the last data value retrieved via the peek - or the commanded poke value is reported in the MM HK packet. This feature is not documented as a requirement or in our Doxygen/user's guide. This has caused confusion for some of our users.

Describe the solution you'd like
Update documentation/requirements to reflect current functionality.

Requester Info
Dan Knutsen
NASA Goddard