doc: clean up the markdown formatting

Just some petty cleanups and formatting fixes so that the Gitlab render is happy.

approved this merge request

added 149 commits

• 2c27616a...8d0d9907 - 148 commits from branch archlinux:master
• 3c5c7f69 - doc: clean up the markdown formatting

Compare with previous version

enabled an automatic merge when the pipeline for 3c5c7f69 succeeds

mentioned in commit 3430e875

merged