Add CI job for docs (backport #367)

[mergify]

ros-controls/control.ros.org#470

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This is an automatic backport of pull request #367 done by Mergify.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 72.63%. Comparing base (6a2c84f) to head (8406862).

Additional details and impacted files

@@           Coverage Diff           @@
##           humble     #368   +/-   ##
=======================================
  Coverage   72.63%   72.63%           
=======================================
  Files          10       10           
  Lines         581      581           
  Branches      223      223           
=======================================
  Hits          422      422           
  Misses        105      105           
  Partials       54       54           

Flag	Coverage Δ
unittests	72.63% <ø> (ø)

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