Allow apps with CREATE_USERS permission to create demo users.

Bug: 31092477
Test: adb shell am create-user --ephemeral --demo <user-name>
Change-Id: Ia08a50ec4371466c62cdc9f5391e298a666b5081
diff --git a/core/res/AndroidManifest.xml b/core/res/AndroidManifest.xml
index 8bdb55e..6c6fd90 100644
--- a/core/res/AndroidManifest.xml
+++ b/core/res/AndroidManifest.xml
@@ -1634,7 +1634,7 @@
 
     <!-- @hide Allows an application to create, remove users and get the list of
          users on the device. Applications holding this permission can only create restricted,
-         guest, managed, and ephemeral users. For creating other kind of users,
+         guest, managed, demo, and ephemeral users. For creating other kind of users,
          {@link android.Manifest.permission#MANAGE_USERS} is needed.
          This permission is not available to third party applications. -->
     <permission android:name="android.permission.CREATE_USERS"