Add documentation on pipeline deletion
Add documentation on pipeline deletion

Add a warning about possible collisions when deleting pipelines.
gocd/developer.go.cd,gocd/docs.go.cd,gocd/developer.go.cd,ketan/docs.go.cd,gocd/developer.go.cd,ketan/docs.go.cd,ketan/docs.go.cd,gocd/docs.go.cd,gocd/docs.go.cd