Update documentation

[gerbaudo]

There are two readme (one in the base dir and one in bash; remove the latter).
We should have one only.
Also, it should check everything out from http (git@github only for devs);
think about a way to easily switch between the http and git@github

@gerbaudo
@dantrim

Note to self: this is what worked for me now:

git clone -b mc15  git@github.com:gerbaudo/susynt-write.git
cd susynt-write/
bash/setup_area.sh 2>&1 | tee install.log
source  bash/setup_release.sh