Fix broken references in documentation

[GandalfDG]

So far I have eliminated 180 warnings about missing reference targets by adding a currentmodule directive to examples.rst. This was an easy fix, but I will continue to chip away at broken references. Also, it might be good to add nitpicky warning output from sphinx-build to the CI process to ensure high-quality documentation

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.32%. Comparing base (6ae673a) to head (02fa078).
Report is 352 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1058   +/-   ##
=======================================
  Coverage   96.32%   96.32%           
=======================================
  Files          40       40           
  Lines        9407     9407           
  Branches     1248     1248           
=======================================
  Hits         9061     9061           
  Misses        204      204           
  Partials      142      142           

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[lorenzncode]

Thanks @GandalfDG. I see this fixes many links in the CadQuery Concepts, Assemblies, and Examples sections.

[jmwright]

Thanks @GandalfDG