Install/Tutorial -- it would be helpful to indicate disk requirements for exemplar cases

[GaryAitken]

It would be helpful if the installation notes (which are excellent, Thank You!) would indicate the disk space requirements for running the exemplar cases. As a new user, I have no idea what those are; exemplar-001 failed with a 20GB disk, then failed again with a 50GB disk, which seems surprising; I'm wondering if something else is going on (but the logs say out of space).