Document multi-set operation
Document multi-set operation

Change-Id: Idedcf941681c95db99ddf240daa03c70e5f4a79e
Reviewed-on: http://review.couchbase.org/25334
Tested-by: Sergey Avseyev <87f6d5e4fd3644c3c20800cde7fd3ad1569370b3@gmail.com>
Reviewed-by: Volker Mische <fb414f8ac0dbbf87663550ae4ef5fc95b1041941@gmail.com>

dewolfe/couchbase-ruby-client,dewolfe/couchbase-ruby-client