Lxplus & NAF documentation

We should definetly create a documentation for new users.

Here are some points I stumbled upon while getting mc-run working on lxplus:
- Logs need to be put on AFS (EOS is not supported) but the default home quota is only 2GB.
- How to increase your AFS quota: https://cern.service-now.com/service-portal?id=kb_article&n=KB0000905
- 10GB is still way to small for e.g. 10k generation jobs. I my testing, 1k Jobs produced a total log of 5.6GB
- The maximum disk one can request at lxplus per job is 20GB
- Streaming of stdout and stderr does not work for all nodes at lxplus

I will try and keep this list updated once I encounter more issues