doc: misc updates for release-process

Signed-off-by: Gary Lowell  <gary.lowell@inktank.com>
Reviewed-by: Ken Dreyer <ken.dreyer@inktank.com>
doc: update release-process for packages

New script to sign rpms in the repo and create the indexes, and
some description of additional packages that might need to be added.

Signed-off-by: Gary Lowell  <gary.lowell@inktank.com>
Reviewed-by: Ken Dreyer <ken.dreyer@inktank.com>
doc: fix reST formatting in release-process

Signed-off-by: Ken Dreyer <ken.dreyer@inktank.com>
doc: rm duplicate info from release-process

The "just push the new tag" bit is already done in the list of commands
above. Remove this piece, since it's duplicated by the "git push"
command above.

The ceph-deploy and backports-sections were empty. Remove them.
Merge pull request #1415 from ceph/wip-build-doc

doc: release-process documentation updates

Reviewed-by: Sage Weil <sage@inktank.com>