Doctrine_Collection docs updated

manual/docs/Basic Components - Collection - Adding new elements.php

+When accessing single elements of the collection and those elements (records) don't exist Doctrine auto-adds them. 
+<br \><br \>
+In the following example
+we fetch all users from database (there are 5) and then add couple of users in the collection.
+<br \><br \>
+As with PHP arrays the indexes start from zero.

manual/docs/Basic Components - Collection - Deleting collection.php

@@ -7,3 +7,7 @@ of users doctrine only performs two queries for this whole transaction. The quer
 <br \><br \>
 DELETE FROM user WHERE id IN (1,2,3, ... ,N)<br \>
 DELETE FROM phonenumber WHERE id IN (1,2,3, ... ,M)<br \>
+<br \><br \>
+It should also be noted that Doctrine is smart enough to perform single-shot-delete per table when transactions are used.
+So if you are deleting a lot of records and want to optimize the operation just wrap the delete calls in Doctrine_Connection transaction.
+

manual/docs/Basic Components - Collection - Getting collection count.php

+The Doctrine_Collection method count returns the number of elements currently in the collection.

manual/docs/Basic Components - Collection - Introduction.php

+Doctrine_Collection is a collection of records (see Doctrine_Record). As with records the collections can be deleted and saved using
+Doctrine_Collection::delete() and Doctrine_Collection::save() accordingly.
+<br \><br \>
+When fetching data from database with either DQL API (see Doctrine_Query) or rawSql API (see Doctrine_RawSql) the methods return an instance of
+Doctrine_Collection by default.
+<br \><br \>
+The following example shows how to initialize a new collection:

manual/docs/Basic Components - Collection - Saving the collection.php

+As with records the collection can be saved by calling the save method.