Initial documentation on stable branches and backporting

[sir-sigurd]

Currently this is mostly for doc fixes.
This is example how it would look like: https://github.com/quiltdata/quilt/commits/version-3.2.1

[drernie]

@sir-sigurd This still looks legit, and was approved. Can you merge? Otherwise, close if not useful.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 38.35%. Comparing base (1823aa6) to head (ffd1b39).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1928   +/-   ##
=======================================
  Coverage   38.35%   38.35%           
=======================================
  Files         778      778           
  Lines       34366    34366           
  Branches     5219     5219           
=======================================
  Hits        13180    13180           
  Misses      20643    20643           
  Partials      543      543           

Flag	Coverage Δ
api-python	91.34% <ø> (ø)
catalog	16.87% <ø> (ø)
lambda	91.48% <ø> (ø)

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[sir-sigurd]

@sir-sigurd This still looks legit, and was approved. Can you merge? Otherwise, close if not useful.

I gave up on having stable branches