migration: add callout for rescheduling mechanism

recently, the multicell team added a component to the in-app
migration guide which allows customers to postpone their
account migration by up to 45 days (this functionality is
currently only available to enterprise tier accounts).

as we begin migrating more enterprise accounts, we want our
public facing docs to highlight this for our users.

website/docs/docs/cloud/migration.md

@@ -15,6 +15,13 @@ Your account will be automatically migrated on or after its scheduled date. Howe
 
 ## Recommended actions
 
+:::info Rescheduling your migration
+
+Customers on dbt Cloud Enterprise tiers can postpone their account migration by up to 45 days. To reschedule your migration, go to **Account Settings** → **Migration guide**.
+
+For help, contact us at [[email protected]](mailto:[email protected]).
+:::
+
 We highly recommended you take these actions:
 
 - Ensure pending user invitations are accepted or note outstanding invitations. Pending user invitations might be voided during the migration. You can resend user invitations after the migration is complete.