Add information on iOS BLE to Bluetooth Page

[JonathanLeeDeKock]

I got stuck here for half a day trying to configure the device to work with my iPhone. I couldn't understand why it wouldn't pair with my phone when it paired just fine with my computer. Finally I read ahead in the instructions and at the very bottom of the GIS software page I found this nugget of information. I almost missed it since most of the GIS software was not relevant to me. I recommend moving this nugget of information up a page so others don't get stuck here quite so easily.

[gdt]

I don't think iti is really true that iOS doesn't support SPP. I think it's more accurate to say that iOS declines to interoperate with SPP that has not paid a fee. As an example i have an OBD2 adpator that works with classic Bluetooth on iOS.

[gdt]

One could say something like "iOS does not interoperate with the standards-compliant Bluetooth SPP imlementation in the RTK Express, but it does work with the BLE implementation". That still steers the users in the right direction.

[JonathanLeeDeKock]

Happy to have it say whatever you'all think is right. Note that I just pulled this exact working from the gis_software.md page, so if changing one, they both should be changed.

[nseidle]

Ya, iOS allows SPP but you have to get a special chip, or get approved, or something. I don't really care to dig into it since BLE seems to be the path forward.

@JonathanLeeDeKock - Sorry for the wasted time and many thanks for the PR! Merging.