Make it clear to users that favourite contacts = BLF keys

Currently, it's not clear for new users that if they mark an extension as a favourite or if they mark a telephone number as a favourite within the Contacts tab, that it would then appear in their BLF on their phone. We need to make it clearer that marking contacts as favourites, in particular marking telephone numbers as favourites, will then send those contacts to the phone, to the desk phone as a BLF. We need to improve the user experience here.