rename this repo cocalc-byoc

[williamstein]

Incidentally, @DrXyzzy 's suggestion of "BYOC = Bring your own compute" as a name for this, is growing on me. It's very evocative, easy to remember, and strangely the phrase "Bring your own compute" is very google-able and barely used online (the top hit right now is some page from 2017 for me just now). It's better than cocalc-compute and cocalc-remote, which both feel ambiguous, whereas "cocalc - bring your own compute" is less unambiguous.