docs(MAINTAINING): add information about CHANGELOG

[jsjoeio]

This PR adds docs around CHANGELOG.

Fixes #3412

Checklist

• updated CHANGELOG.md

[codecov]

Codecov Report

Merging #3467 (cf696f0) into main (8ed578b) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #3467   +/-   ##
=======================================
  Coverage   59.21%   59.21%           
=======================================
  Files          35       35           
  Lines        1709     1709           
  Branches      379      379           
=======================================
  Hits         1012     1012           
  Misses        559      559           
  Partials      138      138           

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