Make translations more visible for user manual

[tflidd]

I just discovered by accident, that the user manual is translated in other languages.

Who would guess that translations are hidden behind there? It's probably even more important than being able to switch between versions.

[p-bo]

As translator, I fully back this idea - it seems, that at least part of Nextcloud users are not benefiting from our work, because it is missed by them (as is evident from this real world example), which is unfortunate…

So, what about to modify documentation rendering template in that manner, that menu section with languages is always (or at least by default) shown please?