doc: move dev setup instructions out of README

(actually removing them from README is a second commit
so that I can update README to point to readthedocs
before pushing it)

Signed-off-by: John Spray <john.spray@redhat.com>
doc: Fix some RST glitches

Signed-off-by: John Spray <john.spray@redhat.com>
Merge pull request #140 from ceph/wip-docs-2

Wip docs 2