Update docs to the correct shell command

doc/raketasks/backup_restore.md

@@ -119,7 +119,7 @@ script on the GitLab task runner pod. For more details, see
 [backing up a GitLab installation](https://gitlab.com/gitlab-org/charts/gitlab/blob/master/doc/backup-restore/backup.md#backing-up-a-gitlab-installation).
 
 ```shell
-kubectl exec -it <gitlab task-runner pod> backup-utility
+kubectl exec -it <gitlab task-runner pod> -- backup-utility
 ```
 
 Similar to the Kubernetes case, if you have scaled out your GitLab cluster to

doc/topics/autodevops/upgrading_postgresql.md

@@ -103,7 +103,7 @@ being modified after the database dump is created.
 1. Connect to the pod with:
 
     ```shell
-    kubectl exec -it production-postgres-5db86568d7-qxlxv --namespace "$APP_NAMESPACE" bash
+    kubectl exec -it production-postgres-5db86568d7-qxlxv --namespace "$APP_NAMESPACE" -- bash
     ```
 
 1. Once, connected, create a dump file with the following command.
@@ -221,7 +221,7 @@ higher*. This is the
 1. Connect to the pod:
 
    ```shell
-   kubectl exec -it production-postgresql-0 --namespace "$APP_NAMESPACE" bash
+   kubectl exec -it production-postgresql-0 --namespace "$APP_NAMESPACE" -- bash
    ```
 
 1. Once connected to the pod, run the following command to restore the database.