The Security Technical Implementation Guide security standard is being
renamed from its release date (`2023-06-08`) to its official version and
revision number (`V5R3`). This helps to align with the version number
being used internally for reporting purposes.
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.
