There was already a check for section duplication, but only in "How to
fix it". This changes the test to cover all sections.
And fixing the rules that this new validation fails on.
Also making test_modify_rule.py run on Windows.
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Co-authored-by: Christophe Zürn <36889251+christophe-zurn-sonarsource@users.noreply.github.com>
Inline adoc files when they are included exactly once.
Also fix language tags because this inlining gives us better information
on what language the code is written in.
