Documentation updates

[abhro]

• Add DLMF reference identifiers
• Add sections to API list
• Clean up docstrings

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 94.10%. Comparing base (c400278) to head (db0d3c3). Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #476   +/-   ##
=======================================
  Coverage   94.10%   94.10%           
=======================================
  Files          14       14           
  Lines        2935     2935           
=======================================
  Hits         2762     2762           
  Misses        173      173           

Flag	Coverage Δ
unittests	94.10% <100.00%> (ø)

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[ViralBShah]

This broadly looks great. Merging it.

[ViralBShah]

@abhro May I request you to see the deployed docs on the dev branch to see if it all looks good? Thanks for the cleanup PR!