brk: Changed account notification balance_ouststanding

New value is payment_due

Author: Josh Sager

src/data/objects/notification.yaml

@@ -57,6 +57,6 @@ enums:
     outage: There is a known outage impacting one or more of your services.
     migration_pending: There is a migration queued for one of your Linodes that you must initiate.
     migration_scheduled: There is a migration queued for one of your Linodes.
-    balance_outstanding: You have a balance on your account that must be paid.
+    payment_due: You have a balance on your account that must be paid.
     xsa: You have a Linode impacted by a Xen Security Advisory which will require migration.
     reboot_scheduled: There is a reboot queued for one of your Linodes.