Updated configure-service-account

Error from server resolved by escaping kubectl patch serviceaccount default -p '{"imagePullSecrets": [{"name": "myregistrykey"}]}' JSON string by '\'

docs/tasks/configure-pod-container/configure-service-account.md

@@ -178,7 +178,7 @@ myregistrykey    kubernetes.io/.dockerconfigjson   1       1d
 Next, modify the default service account for the namespace to use this secret as an imagePullSecret.
 
 ```shell
-kubectl patch serviceaccount default -p '{"imagePullSecrets": [{"name": "myregistrykey"}]}'
+kubectl patch serviceaccount default -p '{\"imagePullSecrets\": [{\"name\": \"acrkey\"}]}'
 ```
 
 Interactive version requiring manual edit: