Add button to disable legacy data rates

Firstly, If you are going to have an auto 'Model' label, please keep the list up-to-date! 

This suggestion is for any Knighthawk WIFI router (but specifically the XR700).

Could you please add a setting to disable legacy data rates. A checkbox to disable legacy 802.11b data rates (1, 2, 5.5, and 11 mbps) is required to improve wireless performance.

Many thanks

Nick