Added warning about relying on habtm table aliases etc

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@1897 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/CHANGELOG

@@ -13,6 +13,11 @@
     end
 
     Post.find(1).comments.search('hi') # => SELECT * from comments WHERE post_id = 1 AND body = 'hi'
+  
+  NOTICE: This patch changes the underlying SQL generated by has_and_belongs_to_many queries. If your relying on that, such as
+  by explicitly referencing the old t and j aliases, you'll need to update your code. Of course, you _shouldn't_ be relying on
+  details like that no less than you should be diving in to touch private variables. But just in case you do, consider yourself
+  noticed :)
 
 * Added migration support for SQLite (using temporary tables to simulate ALTER TABLE) #1771 [Sam Stephenson]