I believe mkdocs raises a warning when it finds a link like this. The repo is setup to abort if any warnings are raised, which should cover this. We should do some proper testing to ensure this actually works, though.

Hrm, mkdocs/mkdocs#192 (comment) hints that to get the automatic validation we should have our links end with .md, which I'd not realised (I think I may have stripped out the .mds when merging the historic stuff).

Since the fix to #17, I think this is now about as well sorted as we can get without adding something of our own on top. I realise this issue was originally about doing that, however the value that adds is fairly limited now we've got mkdocs doing most of the checking.

Closing this as no longer useful, though happy to be disagreed with if there's a strong feeling we need something more.