Fixed typo in errors list.

Change-Id: Ie4fdacb6958542c43c18cd63fc86580702ea41e8
Reviewed-on: http://review.couchbase.org/28766
Tested-by: Brett Lawson <brett19@gmail.com>
Reviewed-by: Mark Getz <mark.getz@kellpro.com>
Reviewed-by: Mark Nunberg <mnunberg@haskalah.org>