ci: Refine lints

[cpswan]

We have been suppressing two rules:

• md013 - long lines - needed because tables contain long lines
• md024 - multiple headings with the same content - as we repeat (sub)headings in some docs

The first is the most problematic, as it means new docs with long lines that aren't necessary still pass tests.

- What I did

• Individual pragmas around where we do need long lines
• Config file to allow repeat headings in siblings only
• Rework workflow to use config file

- How I did it

I wanted to use a command line setting rather than config file, but couldn't get it to work hence config file and https://github.com/jackdewinter/pymarkdown/issues/1000

- How to verify it

Clean ci run against this PR

- Description for the changelog

ci: Refine lints