few more docs

Hi,

although I might touch these sources again tomorrow, I thought it's good to open a PR in order to receive early feedback (mostly of crude type about missing pieces/paragraphs). Yet, any feedback is welcome :)

tia, F.
Hmm, not sure if this is the right location for this. If they happen to have an older version, EasyBuild will spit out a pretty clear error message.
I wouldn't scare people with big red boxes in the installation instructions...