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.
IMHO, because it is an "error" right now, it is better to tune expectations in advance in the documentation, no? 

Since Lmod is now buildable via EB and usable by it, as well, I think reconsidering hard-failing on env-modules-C<3.2.10 worths a thought, because it could help these fellows make a step forward.

My position: let's discuss this together and act accordingly (you with the final say anyhow).