doc: update README to refer to detailed instructions
doc: update README to refer to detailed instructions

The stuff that used to be front and center (and
quite confusing) is now relegated to the development
documentation.

Signed-off-by: John Spray <a0ab4ec42db5a70bbcbfc74d8971c0305528d92b@redhat.com>

r0h4n/ceph-integration