Commit 
cd467caf renamed notmuch_query_search to notmuch_query_search_messages.
Commit 
1ba3d46f created notmuch_query_search_threads. We better keep the docs
of notmuch_query_create consistent with those changes.
Signed-off-by: Fernando Carrijo <fcarrijo@yahoo.com.br>
Edited-by: Carl Worth to explicitly list the full name of each
function being referenced.
 
  * As a special case, passing a length-zero string, (that is ""), will
  * result in a query that returns all messages in the database.
  *
- * See notmuch_query_set_sort for controlling the order of results and
- * notmuch_query_search to actually execute the query.
+ * See notmuch_query_set_sort for controlling the order of results.
+ * See notmuch_query_search_messages and notmuch_query_search_threads
+ * to actually execute the query.
  *
  * User should call notmuch_query_destroy when finished with this
  * query.