api/update-message: Make it render correctly in Github.

templates/zerver/api/update-message.md

@@ -38,6 +38,7 @@ curl -X "PATCH" {{ api_url }}/v1/messages/<msg_id> \
 </div>
 
 <div data-language="python" markdown="1">
+
 ```python
 #!/usr/bin/env python
 
@@ -53,6 +54,7 @@ print(client.update_message({
 }))
 
 ```
+
 </div>
 
 <div data-language="javascript" markdown="1">