The alpha, beta, and stable channels do not match the rook release process.
Each storage provider defines their own stability based on the CRDs
rather than defining it with the release process. Rook really
only has two release streams: master and the official releases.
Master is published with each merge, while releases go through
a signoff process to ensure quality. Thus, the alpha, beta,
and stable channels are removed and replaced with a
single release channel.
Signed-off-by: travisn <tnielsen@redhat.com>