docs: More docstrings and comments for gate kernels

[kshyatt-aws]

Issue #, if available: N/A

Description of changes: Added lots more info about what methods are doing and why, added more docstrings as well

Testing done: Tests and doc build passed locally

Merge Checklist

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General

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.27%. Comparing base (0261648) to head (f1d1f80).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #62   +/-   ##
=======================================
  Coverage   98.27%   98.27%           
=======================================
  Files          21       21           
  Lines        2197     2197           
=======================================
  Hits         2159     2159           
  Misses         38       38           

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