MM doc: wwan device types and port detection

[Aleksander Morgado]

Hey hey,

A pair of new pages in the MM documentation in the website are now
available, in case you're interested, see the new "WWAN device types"
and "Port and device detection" sections in
https://modemmanager.org/docs/modemmanager/

If you find things to fix or improvements that could be useful, please
create new merge requests in the website doc repository:
https://gitlab.freedesktop.org/mobile-broadband/mobile-broadband.pages.freedesktop.org

Cheers!
-- 
Aleksander