Add no-op `-r` flag back to manifest-generation script
Add no-op `-r` flag back to manifest-generation script

* Update deprecation notices on `-b`, `-k`, and `-r` flags
* `-k` flag no longer requires an argument

[finishes #119433481]

cloudfoundry-incubator/diego-release,cloudfoundry-incubator/diego-release,cloudfoundry-incubator/diego-release,cloudfoundry-incubator/diego-release