Update docs infrastructure and make minor fixes

[abhro]

• Use Documenter v1
• Use [sources] section in docs/Project.toml to pin dependency on self to current working version (this also requires the newer Julia, I think >=v1.11 on the docs workflow)
• Fix some intra-documentation links
• Add docstrings to a doc page

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (b70b27c) to head (699305c).
⚠️ Report is 7 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##            master       #74   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           12        12           
  Lines          786       786           
=========================================
  Hits           786       786           

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[disberd]

Thanks again for you interest in this project and for the contribution to it!