Update sidebar

 - Add link to actual GSG
 - Add Tutorials section
 - Clean up Understanding section

SIDEBAR.md

@@ -4,19 +4,26 @@ Related Resources
 
 There's more to building RESTful web services than is covered here. You may want to continue your exploration of Spring and REST with the following
 
-### Getting Started guides:
+### Getting Started Guides
 
 * Handling POST, PUT, and GET requests in REST services
 * Creating self-describing APIs with HATEOAS
-* Securing a REST service with HTTP Basic
 * Securing a REST service with OAuth
-* Consuming REST services
-* Testing REST services
+* [Consuming RESTful web services][gs-consuming-rest]
+* Testing RESTful web services
+
+[gs-consuming-rest]: /guides/gs/consuming-rest/content
+
+### Tutorials
+
+* [Tutorial TBD][tut-tbd]
+
+[tut-tbd]: /guides/tutorials/tbd
 
 ### Understanding
 
-* [Understanding REST][u-rest]
-* [Understanding Json][u-json]
+* [REST][u-rest]
+* [JSON][u-json]
 
 [u-rest]: /understanding/rest
 [u-json]: /understanding/json