Remove private steps in Compare Documentation

[syntagmatic]

Remove eferences to studio.stamen.com and Stamen's version of Compare, including our Github repo (except in historical project notes)

This will be the canonical version of Compare:

https://holos.berkeley.edu/compare/

Built from this repo:

https://github.com/berkeley-gif/ecoengine-compare

[syntagmatic]

Done, and pull request filed.

berkeley-gif/ecoengine-compare#1