User suitable documentation of multi_deps dependencies

[jhein32]

I need to request an upgrade to EasyBuild, such that users can see the choices of packages they have for a multi-depspackage. Example for the new scipy-bundle they need to find out which Python 2.7 version needs to go with this specific scipy-bundle.

I think the output of module show or digesting the lua/tcl source of the module is not good enough, since non-inteligible to many new users to our system.

If the multi-deps command would print a statement like:

This package supports Python/3.7.1 and Python/2.7.15

into the module help and module whatis, I think this could be communicated.

[akesandgren]

@jhein32 See the proposed solution.

[boegel]

Considered fixed via #2882