Update site/en/community/mailing-lists.md

Author: 8bitmp3

site/en/community/mailing-lists.md

@@ -2,7 +2,8 @@
 
 As a community, we do much of our collaboration on public mailing lists. Please
 note that if you're looking for help using TensorFlow,
-[Stack Overflow](https://stackoverflow.com/questions/tagged/tensorflow), [TensorFlow Forum](https://discuss.tensorflow.org/) and
+[TensorFlow Forum](https://discuss.tensorflow.org/),
+[Stack Overflow](https://stackoverflow.com/questions/tagged/tensorflow), and
 [GitHub issues](https://github.com/tensorflow/tensorflow/issues) are the best
 initial places to look.