Add documentation for Assistant

[misscoded]

Summary

Adds accompanying documentation for Assistant class. Initial commit is based off of the Python documentation, but needn't stay that way.

Requirements (place an x in each [ ])

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.21%. Comparing base (1ebd657) to head (f38748d).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2293   +/-   ##
=======================================
  Coverage   81.21%   81.21%           
=======================================
  Files          21       21           
  Lines        1799     1799           
  Branches      498      498           
=======================================
  Hits         1461     1461           
  Misses        218      218           
  Partials      120      120           

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[misscoded]

@lukegalbraithrussell 👋🏼 Initial draft, based on the Python version that was published. Feel free to make use of this branch for any additional changes you see fit. It's in your hands now!

[misscoded]

Closing this as #2295 has been opened instead for the same purpose.