Define guidelines for resource fields

[mschubert]

There are some kinds of resources that are very common to use, e.g. mem, <wall>time, cores, etc.

It would be nice if the documentation provided a list of which resource types should be implemented by profiles and which common names to use to refer to those resources.

This would make the whole collection more portable.

[johanneskoester]

Yes, indeed. I actually wanted to wait until I have done #3.