Fix label yml

I was getting: invalid value 'map[]': selector does not match template with the -

examples/walkthrough/k8s201.md

@@ -47,7 +47,7 @@ desiredState:
     # Important: these labels need to match the selector above
     # The api server enforces this constraint.
     labels:
-      - name: nginx
+      name: nginx
 ```
 
 ### Services