(custom-flows/user-impersonation) mention needing to create the custo…

…m perm (#2020)

docs/custom-flows/user-impersonation.mdx

@@ -11,7 +11,7 @@ This guide will walk you through how to build a custom flow that handles user im
 
 <Tabs items={["Next.js", "Expo"]}>
   <Tab>
-    The following example builds a dashboard that is only accessible to users with the `admin:impersonate` [permission](/docs/organizations/roles-permissions#custom-permissions). You can modify the [authorization checks](/docs/organizations/verify-user-permissions) to fit your use case.
+    The following example builds a dashboard that is only accessible to users with the `org:admin:impersonate` permission. To use this example, you must first [create the custom `org:admin:impersonate` permission](/docs/organizations/roles-permissions#custom-permissions). Or you can modify the [authorization checks](/docs/organizations/verify-user-permissions) to fit your use case.
 
     In the dashboard, the user will see a list of the application's users. When the user chooses to impersonate a user, they will be signed in as that user and redirected to the homepage.