Fix config example

clearml_agent/backend_api/config/default/agent.conf

@@ -250,7 +250,13 @@
     #       path: "/tmp/fox.txt"
     #     }
     #     myjsonfile {
-    #       contents: {some: nested: value: [1, 2, 3, 4]}
+    #       contents: {
+    #         some {
+    #           nested {
+    #             value: [1, 2, 3, 4]
+    #           }
+    #         }
+    #       }
     #       path: "/tmp/test.json"
     #       target_format: json
     #     }