Docs: Fix a quanta of broken external links
Problem to solve
Over time, links within the documentation have become broken, and while testing identifies these links, there's an accumulated amount of them that need to be fixed.
Further details
Marcel (in the last TW meeting) provided a link to a run that identified many of these broken links: !33879 (merged)
Proposal
Fix a certain amount (whatever can be done in a day or two) of the identified broken links within the documentation, to help us get to a place where this can be a recurring (and achievable) chore.