[Dxspider-support] Add 500kHz (600m) to the band list

[Bela Markus]

Hi,

as there are few countries issue experimental licences for the 500kHz 
(600m) band, would be good to add to the band list. I have seen just 
recently 600m spots hijacking the 136kHz.

600m doesn't fit to VLF or HF group, the right place wouth be LF even if 
would be alone there.

Regards... Béla, HA5DI