Docs: update built-in server description

docs/deploying/index.rst

@@ -4,9 +4,8 @@ Deployment Options
 ==================
 
 While lightweight and easy to use, **Flask's built-in server is not suitable
-for production** as it doesn't scale well and by default serves only one
-request at a time.  Some of the options available for properly running Flask in
-production are documented here.
+for production** as it doesn't scale well.  Some of the options available for
+properly running Flask in production are documented here.
 
 If you want to deploy your Flask application to a WSGI server not listed here,
 look up the server documentation about how to use a WSGI app with it.  Just