Update Botswana codes list

[Fooba24]

Please see https://www.itu.int/dms_pub/itu-t/oth/02/02/T020200001C0009PDFE.pdf

1.5. MOBILE NUMBERS
    1.5.1. Level 7 and 8
        Levels 7 and part of Level 8 are an eight digits long mobile number range from :
        71 XXX XXX to 78 XXX XXX ; and
        81 XXX XXX to 85 XXX XXX respectively.

[dongri]