Update release-candidate-guide.md

Author: sofietoft

15/umbraco-cms/release-candidate-guide.md

@@ -63,6 +63,9 @@ Here is a list of all the articles that are new to this version or have been upd
 ### New articles
 
 * [Tutorial: Extending the Help Menu](tutorials/extending-the-help-menu.md)
+* [Creating a Custom Seed Key Provider](extending/creating-custom-seed-key-provider.md)
+* [Cache Settings](reference/configuration/cache-settings.md)
+* [Cache Seeding](reference/cache/cache-seeding.md)
 
 ### Updated articles