When an include is not surrounded by empty lines, its content is inlined
on the same line as the adjacent content. That can lead to broken tags
and other display issues.
This PR fixes all such includes and introduces a validation step that
forbids introducing the same problem again.
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.
* Change description and add some comments
* Update the description of what the C# implementation actually does for now
* Fix a typo
* Small formatting change on S2198
* Small formatting changes on S2198
* Small formatting change on S2198
