Add syntax highlighting to supervision tree

README.md

@@ -33,13 +33,17 @@ end
 
 Once you have created your cluster, add it to your application's supervision tree:
 
-    children = [
-      MyApp.ElasticsearchCluster
-    ]
+```elixir
+children = [
+  MyApp.ElasticsearchCluster
+]
+```
 
 Finally, you can issue requests to Elasticsearch using it.
 
-    Elasticsearch.get(MyApp.ElasticsearchCluster, "/_cat/health")
+```elixir
+Elasticsearch.get(MyApp.ElasticsearchCluster, "/_cat/health")
+```
 
 ## Configuration