pop_som_frc tools

Looks like these did not get migrated over to CDEPS. I actually need to update these, but can we at least put a version here?

https://github.com/ESMCI/cime/tree/cime5.6.50/src/components/data_comps/docn

There was also a whitepaper on the SOM that used to be under the old documentation hierarchy. I would like to point to this again if possible.