fix: Doc URL by version

[EL-File4138]

Superficial fix to provide more clear guidance for now with minimum extra components. Various non-canonical build have been considered to the best extend.

[arch1t3cht]

This would at least need some cooperation from the website to redirect unknown versions to latest, right? Otherwise a 3.4.x version might point users to https://docs.aegisub.org/3.4/Main_Page/ which shows a 404 (and there'd always be the risk of publishing a release and forgetting to add a new docs version). Linking to an outdated docs page is probably better than an error message.

Personally I'd prefer to just leave the linked version explicit in the documentation - that gives more freedom to e.g. skip versions in the docs. IIRC it's also not yet decided whether we'll even continue this convention of having a separate doc page for every old version or whether we'll just use latest from now on.

[EL-File4138]

This would at least need some cooperation from the website to redirect unknown versions to latest, right?

Of course, and I would like to point out that AegiSite is inherently much easier than the application itself to implement such workaround should issue arises.

Personally I'd prefer to just leave the linked version explicit in the documentation - that gives more freedom to e.g. skip versions in the docs. IIRC it's also not yet decided whether we'll even continue this convention of having a separate doc page for every old version or whether we'll just use latest from now on.

For the same reason, I think that automating this update to an extent is better than adding a checklist item before every release, which tends to be forgotten easily and produce more workload to amend, and confusion among users (Considering how many new issue reports still use old version as comparison, and many didn't even notice the need to update). If the latter is eventually decided upon, we can implement a simple redirect on AegiSite, and all past versions will be on the same page.