Use 127.0.0.1 instead of `hostname` in the "access the web app" section.

docs/sources/examples/python_web_app.rst

@@ -71,7 +71,7 @@ lookup the public-facing port which is NAT-ed store the private port used by the
 .. code-block:: bash
 
     # install curl if necessary, then ...
-    curl http://`hostname`:$WEB_PORT
+    curl http://127.0.0.1:$WEB_PORT
       Hello world!
 
 access the web app using curl. If everything worked as planned you should see the line "Hello world!" inside of your console.