Document tags in ESCOMP/CAM

From Steve Goldhaber - he suggests:

"While the cam_development branch changes over time, we frequently create and document tags to provide stable test points which can be checked out anytime in the future."

It would be nice to get something like this in the main (or announce?) README.md file. I was also thinking that we should have a 'guide to CAM tag names' documentation somewhere (either in the README or on the wiki). This would help users understand the various patterns in the tags