Update automation instructions for DB setup

doc/development/rake_tasks.md

@@ -88,13 +88,14 @@ bundle exec rake 'gitlab:seed:development_metrics[your_project_id]'
 ### Automation
 
 If you're very sure that you want to **wipe the current database** and refill
-seeds, you could:
+seeds, you can set the `FORCE` environment variable to `yes`:
 
 ```shell
-echo 'yes' | bundle exec rake setup
+FORCE=yes bundle exec rake setup
 ```
 
-To save you from answering `yes` manually.
+This will skip the action confirmation/safety check, saving you from answering
+`yes` manually.
 
 ### Discard `stdout`