Fix all the anchors
I'm going to use this issue to track the progress of fixing the anchors, now that there is a good tool for finding them thanks to https://gitlab.com/gitlab-com/gitlab-docs/merge_requests/397
Edit: Once all below are merged, there should be NO MORE broken anchors, from 578 at the start! (ignoring any new broken anchors, or ones that I accidentally missed)
Edited by Marcel Amirault