[WIP] Docs/gen section refactor

[jlnav]

Mostly small adjustments so far, plus experimenting with splitting the gens toctree into categories.

Addresses #1412

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 76.59%. Comparing base (2aac3fa) to head (e3571cd).
Report is 83 commits behind head on develop.

❗ There is a different number of reports uploaded between BASE (2aac3fa) and HEAD (e3571cd). Click for more details.

HEAD has 16 uploads less than BASE

Flag	BASE (2aac3fa)	HEAD (e3571cd)
	26	10

Additional details and impacted files

@@             Coverage Diff              @@
##           develop    #1418       +/-   ##
============================================
- Coverage    92.72%   76.59%   -16.13%     
============================================
  Files           88       88               
  Lines         8055     8055               
  Branches      1442     1442               
============================================
- Hits          7469     6170     -1299     
- Misses         385     1666     +1281     
- Partials       201      219       +18     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[jlnav]

Closing until we've made more progress on ask/tell