kern/Makefile.base: use QUIETFLAGS instead of MAKEFLAGS

For some reason that I cannot explain, and do not care to debug, MAKEFLAGS was
being set to "w" when make was being invoked with -C from another directory, ie.
make -C kern.

Since I want to be able to have the top level make the kernel, this needed to be
fixed.
Makefile: make the top level makefile kernel aware

I use to have this, and it never worked properly. I believe that it should work
now.
README: Now that I mirror on github, add a README

I've wanted to add a README for a while, with useful information. Unfortunately,
I do not have time to do this, but because github automatically displays your
README, I wanted to put something on there.