mmcli man page update for bands

[matthew stanger]

Hi,

I noticed the man page for mmcli had the string incorrect for setting bands.

https://www.freedesktop.org/software/ModemManager/man/1.8.0/mmcli.8.html

All versioned pages show:
       --set-bands=[BAND1|BAND2|...]

it should be:
       --set-current-bands=[BAND1|BAND2|...]

The string was changed in 'mmcli-modem.c' at commit
212d00c529ee07131bf3b71a8759dca49292c059. I'm guessing not many people
want to limit their modems by setting this stuff but since I'm
involved in hacky hardware that can only pass certification labs by
turning off bands I thought I'd point it out ¯\_(ツ)_/¯

Cheers,