Updated UPGRADE file.

UPGRADE_TO_2_0

@@ -3,9 +3,9 @@
 
 ## Console migrated to Symfony Console
 
-The Doctrine Cli has been replaced by Symfony Console Configuration
+The Doctrine CLI has been replaced by Symfony Console Configuration
 
-Instead of having to specifiy:
+Instead of having to specify:
 
     [php]
     $cliConfig = new CliConfiguration();
@@ -100,9 +100,22 @@ The "default" option for database column defaults has been removed. If desired,
 be implemented by using the columnDefinition attribute of the @Column annotation (or the approriate XML and YAML equivalents).
 Prefer PHP default values, if possible.
 
-## Partial Objects
+## Selecting Partial Objects
 
-[TBD: New syntax, results, etc.]
+Querying for partial objects now has a new syntax. The old syntax to query for partial objects
+now has a different meaning. This is best illustrated by an example. If you previously
+had a DQL query like this:
+
+    [sql]
+    SELECT u.id, u.name FROM User u
+    
+Since BETA1, simple state field path expressions in the select clause are used to select
+object fields as plain scalar values (something that was not possible before).
+To achieve the same result as previously (that is, a partial object with only id and name populated)
+you need to use the following, explicit syntax:
+
+    [sql]
+    SELECT PARTIAL u.{id,name} FROM User u
 
 ## XML Mapping Driver
 
@@ -133,3 +146,9 @@ by using the API on the `PreUpdateEventArgs` instance passed to the preUpdate li
 to the state of the entitys properties won't affect the database UPDATE statement anymore. This gives drastic
 performance benefits for the preUpdate event.
 
+## Collection API
+
+The Collection interface in the Common package has been updated with some missing methods
+that were present only on the default implementation, ArrayCollection. Custom collection
+implementations need to be updated to adhere to the updated interface.
+