update issue link

doc/user/project/clusters/runbooks/index.md

@@ -15,7 +15,7 @@ code blocks or database queries against a given environment.
 
 ## Nurtch Executable Runbooks
 
-> [Introduced](ce-45912) in GitLab 11.4.
+> [Introduced](https://gitlab.com/gitlab-org/gitlab-ce/issues/45912) in GitLab 11.4.
 
 The JupyterHub app offered via GitLab’s Kubernetes integration now ships 
 with Nurtch’s Rubix library, providing a simple way to create DevOps