Investigate a way to make externalized rdoc as flat as possible, preferably a solution that matches Rubocop defaults requirements

[psychoslave]

Currently Rubocop is configured with

Lint/EmptyClass:
  AllowComments: true

This is because otherwise lib/documentation.rb will trigger complaints about empty classes, that only contain documentation coded as Rdoc comments.

It would be nice to have a way to document these information that:

• preserve externalization of these long explanation paragraphs
• [ ] doesn't require to have the most of the file with lines starting with # comment operator
• [ ] asks no specific Rubocop parameter

Note on the later point that it's exclude the =BEGIN rdoc as Rubocop defaults doesn't like it.

References

• https://ruby-doc.org/stdlib-1.8.6/libdoc/rdoc/rdoc/RDoc.html#module-RDoc-label-Markup