docs: append coding guidelines to maintainer docs

[phm07]

[codecov[bot]]

Codecov Report

:white_check_mark: All modified and coverable lines are covered by tests. :white_check_mark: Project coverage is 80.05%. Comparing base (6afa559) to head (371ac64).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #790   +/-   ##
=======================================
  Coverage   80.05%   80.05%           
=======================================
  Files          60       60           
  Lines        4452     4452           
=======================================
  Hits         3564     3564           
  Misses        587      587           
  Partials      301      301           

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[jooola]

Do not hesitate to also use actual code with a lot of comments to describe patterns.