Keep the Bst2html output up to date.

Description

This MR fixes the stale bst html examples in the doc's and make it easier to maintain the .run files.

Proposed changes

The CI should re run bst2html for all run files remove the cache of html files as it is no longer needed (and stale) cause bst2html to rerun if the .run file is newer than the html from the last time you ran make -C doc

Compromises:

• This dose mean that the doc CI runner will be slower but it will still be a lot faster than the other tests.
• This also means that the first time you run make -C doc it will take slightly longer.

Note: you can see what he new doc's look like by downloading the doc's artifact from the pipeline.

Task or bug number that this MR solves

This merge request, when approved, will close issue/bug: #778 (closed)