hello-nais: fix i github action

docs/tutorials/hello-nais.md

@@ -143,7 +143,7 @@ Add the following content to the file, and insert the appropriate values in the
             CLUSTER: <MY_CLUSTER> # Replace (1)
             RESOURCE: .nais/app.yaml # This points to the file we created in the previous step
             VAR: image=${{ steps.docker-build-push.outputs.image }}
-            VAR: image=${{ steps.docker-build-push.outputs.telemetry }}
+            TELEMETRY: ${{ steps.docker-build-push.outputs.telemetry }}
     ```
 
     1.  Cluster in this context is the same as the environment name. You can find the value in [workloads/environments](../workloads/reference/environments.md).