Fix typo in 4.0.md (#950)

Author: RichieB2B

docs/migration-guide/4.0.md

@@ -54,15 +54,15 @@ Tasks are `SYSTEM` or `VALIDATE` workflows that are run in the context of a syst
 Example on how to update the `target` and `is_task` for all workflows that start with `validate_`:
 
 ```sql
-UPDATE workflow
+UPDATE workflows
 SET target = 'VALIDATE', is_task = TRUE
 WHERE name LIKE 'validate_%';
 ```
 
 Example on how to update the `target` and `is_task` for all workflows that are `SYSTEM` or `VALIDATE`:
 
 ```sql
-UPDATE workflow
+UPDATE workflows
 SET is_task = TRUE
 WHERE target IN ('SYSTEM', 'VALIDATE');
 ```