Update search_keywords example to match current API

Change-Id: I9a8971d5af73b73e1e77ea692984d6148170a6b3
Reviewed-on: http://review.couchbase.org/27057
Tested-by: Mordechai Nunberg <mnunberg@haskalah.org>
Reviewed-by: Matt Ingenthron <matt@couchbase.com>