Fix a typo in toy-indexing.xml

Change-Id: Ie85209f48ac8b82f975aa5c9e4636aa300f7f02d
Reviewed-on: http://review.couchbase.org/41598
Reviewed-by: Sarath Lakshman <sarath@couchbase.com>
Tested-by: Sarath Lakshman <sarath@couchbase.com>