Clean up some rotten bits from our doc

While going through the whole documentation for #11916 (closed) I spotted and cleanup some rotten bits on our website. These are small unrelated bits so I’m sorry but the subject of this ticket is so generic (but the commits are atomic). I also didn’t want to wait until 3.0, so here is a branch.

Feature Branch: doc/11942-rotten-bits

Related issues

Blocks #12432 (closed)

Original created by @sajolida on 11942 (Redmine)

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