Typo fix.

Signed-off-by: Sam Kleinman <samk@10gen.com>

Author: puentesarrin

source/release-notes/2.6.txt

@@ -435,7 +435,7 @@ Changes Affecting Compatibility
 
 Some changes in 2.6 can affect :doc:`compatibility
 </release-notes/2.6-compatibility>` and may require user actions. The
-2.6 :program:`mongo` shell provides an
+2.6 :program:`mongo` shell provides a
 :method:`db.upgradeCheckAllDBs()` method to perform a check for upgrade
 preparedness for some of these changes.