Docs say maximum priority is 3 while the real maximum is 4 #379

In the wallet-rpc docs, under both transfer and transfer_split, it says that accepted values for priority are 0-3 and then lists 5 things they correspond to: default, unimportant, normal, elevated, priority.

The actual maximum priority value is 4 as seen in the on_transfer function where it calls fee_priority_utilities::is_valid which checks whether the priority is less than or equal to 4.