bi_view_editor: window functions without ORDER BY clause do not have reliable behavior

bi_view_editor/readme/ROADMAP.rst

@@ -5,3 +5,4 @@
 * Data the user has no access to (e.g. in a multi company situation) can be
   viewed by making a view. Would be nice if models available to select when
   creating a view are limited to the ones that have intersecting groups.
+* Raise a warning in case the SQL query is not correct.

bi_view_editor/readme/USAGE.rst

@@ -21,3 +21,6 @@ To access the created BI View with a dedicated menu:
 A more advanced UI is also available under the "Details" tab. It provides extra
 possibilities for more advanced users, like to use LEFT JOIN instead of the
 default INNER JOIN.
+
+It also possible to improve the IDs generation for new views by adding an `Over Condition` in the "SQL" tab, see https://www.postgresql.org/docs/current/sql-expressions.html#SYNTAX-WINDOW-FUNCTIONS for further details.
+For instance, an ORDER BY clause helps preventing unreliable behavior when filtering the generated views.