The GUIDE.md file had become a bulky misc file. The BEGINNERS.md file
had both redundancy with other files and had value for non-beginners in
talking about our code specifically.

Now, README now longer has build instructions, that's in BUILD.md

README includes new information about getting in touch.

BEGINNERS is renamed to CONTRIBUTING and still is accessible to
beginners but includes more of the details about all the areas needed to
get set up, contribute, figure things out, understand our development
values, etc.

new files added for TEXTEDITORS (which includes more info now and
references Atom, which is probably the most newbie-friendly FLO option
today) and for DATABASE-MANAGEMENT (which is basically the unchanged
stuff from GUIDE that was appendixes and such).

Among all sorts of different priorities, the goal is to have mostly only
one place for any particular bit of information, so only one place to
need to find it or update it.