feat(doc_x_workcat): add unique constraint

updates/36/36013/utils/tablect.sql

@@ -0,0 +1,7 @@
+/*
+This file is part of Giswater 3
+The program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
+This version of Giswater is provided by Giswater Association
+*/
+
+alter table doc_x_workcat add constraint unique_doc_id_workcat_id unique (doc_id, workcat_id);