Move contributing and developer docs to recommended

[abelsiqueira]

These files are overkill for a minimal case. They can, in the
future, come back as simpler versions on the minimal case. However,
thinking about, for instance, a solo dev kickstarting the package and
using the minimal (so no formatter, no issue templates, no linting), it
won't make sense to have all these guidelines in place.

Closes #313

Breaking change: If you have are using the minimal version, this will
remove the files docs/src/90-contributing.md and
docs/src/91-developer.md.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (d05e649) to head (5742796).

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #339   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            2         2           
  Lines           57        57           
=========================================
  Hits            57        57           

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