Fix markdownlint

Author: lfrancke

README.md

@@ -94,9 +94,8 @@ nn/simple-hdfs.default.svc.cluster.local@CLUSTER.LOCAL : admin superuser
 
 and the Hadoop logs will show that the lookup has taken place:
 
-```
+```text
 - Calling StackableGroupMapper.getGroups for user [nn]
 - Opa response [{"result":{"groups":{"groups":["/admin","/superuser"]},"users_by_name":{"alice":{"customAttributes":{},"groups":["/superset-admin"],"id":"af07f12c-1234-40a7-93e0-874537bdf3f5","username":"alice"},"bob":{"customAttributes":{},"groups":["/admin"],"id":"af07f12c-2345-40a7-93e0-874537bdf3f5","username":"bob"},"nn":{"customAttributes":{},"groups":["/admin","/superuser"],"id":"af07f12c-7890-40a7-93e0-874537bdf3f5","username":"nn"},"stackable":{"customAttributes":{},"groups":["/admin","/superuser"],"id":"af07f12c-3456-40a7-93e0-874537bdf3f5","username":"stackable"}}}}
 - Groups for [nn]: [[admin, superuser]]
 ```
-