Merge pull request rails#11564 from zzak/active_model_guide

[Guides] Active Model Basics [ci skip]

Author: senny

guides/source/documents.yaml

@@ -32,6 +32,12 @@
       name: Active Record Query Interface
       url: active_record_querying.html
       description: This guide covers the database query interface provided by Active Record.
+
+    -
+      name: Active Model Basics
+      url: active_model_basics.html
+      description: This guide will get you started using model classes, and non-Active Record models.
+      work_in_progress: true
 -
   name: Views
   documents: