Update change log for #2250.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@2372 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/CHANGELOG

 *SVN*
 
+* Extensive documentation for the abstract database adapter.  #2250 [François Beausoleil <fbeausoleil@ftml.net>]
+
 * Clean up Fixtures.reset_sequences for PostgreSQL.  Handle tables with no rows and models with custom primary keys.  #2174, #2183 [jay@jay.fm, Blair Zajac <blair@orcaware.com>]
 
 * Improve error message when nil is assigned to an attr which validates_size_of within a range.  #2022 [Manuel Holtgrewe <purestorm@ggnore.net>]