Introduce information for migration from legacy -> new

source/migration.rst

@@ -0,0 +1,40 @@
+Migration from UH Enterprise/UH VPN Desktop
+===========================================
+
+With the introduction of UH VPN, the old "UH Enterprise"/"UH VPN Desktop" apps are
+no longer supported and will no longer receive security and performance updates.
+
+All clients should migrate to "UH VPN" on their relevant App Store, and request
+new profiles from their Group administrator.
+
+Notes for Apple Platform Users
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Clients on Apple platforms may wish to wipe profiles from the old app before
+uninstalling the old app.
+
+- To do this on iOS, go to "Manage Profiles" and then delete all of the profiles
+  one by one by swiping them to the left.
+- To do this on macOS, open "Manage Profiles" and then click on the settings cog
+  button at the bottom left of the table and press "Remove All Profiles".
+
+If you did not remove profiles before uninstalling the old app, get your Group
+administrator to revoke old profiles.  Alternatively on macOS:
+
+1. Open Spotlight (``Cmd + Space``) and search for "Keychain Access".
+2. Under the "login" Keychain on the left pane, look for an entry called
+   "UH Enterprise Secure Profile Storage"
+3. Delete the Keychain Entry by right clicking on it and pressing "Delete ..."
+
+Notes for Android Platform Users
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Uninstalling the app will remove profiles from the device.
+
+If on Android 10 ensure that "Keep XXX of app data." is **not** ticked when
+uninstalling the app.
+
+Notes for Windows Platform Users
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Disregard this information as a legacy Windows client was never produced.