docs: add stable channel to rook ceph helm chart docs
docs: add stable channel to rook ceph helm chart docs

Signed-off-by: Jared Watts <d81dfc8bbf0a29009cd655fe5ce0d82500efb58c@gmail.com>

rook/nfs,rook/rook,rook/rook,rook/rook,rook/nfs,rook/nfs,rook/rook,rook/rook