version selection disappeared from documentation

[lzehl]

Below the logo on the left side menu we listed the openMINDS versions. It might be a stupid thing (e.g. too many versions now to display), or an actual bug in the code now. We need to fix this (I can try but I may need help with this).

[lzehl]

@Raphael-Gazzotti the version switcher in readthedocs switched to floating container instead of being embedded below the logo in the menu sidebar. Can you investigate why and how we can change this back?