added missing ! on link for extending sails doc

added missing ! on the link for extending sails doc

0.11-migration-guide.md

@@ -108,7 +108,7 @@ Most of the features you're familiar with in Sails have actually already been im
 + `http`       _(which provides an HTTP server)_
 + and 16 others.
 
-You can read more about how to write your own hooks in the [new and improved "Extending Sails" documentation](http://sailsjs.org/#/documentation/concepts/extending-sails) on http://sailsjs.org.
+You can read more about how to write your own hooks in the [new and improved "Extending Sails" documentation](http://sailsjs.org/#!/documentation/concepts/extending-sails) on http://sailsjs.org.
 
 
 #### Socket.io v1.x