Update wifi-dongles.md

[aethernet]

This pages information looks out of date and is quite confusing when working with CM3 or older pi.
So added notes about AP mode support and deprecation of rtl-8192cu drivers in balena os.

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Please make sure to read the CONTRIBUTING document before opening the PR for relevant information on contributing to the documentation. Thanks!

[floion]

Hi @aethernet which rtl8192cu dongle have you tried and it did not work? Also on which OS version and on what board?

[aethernet]

It was an Edimax EW-7811Un on pi 3 (actually a CM3 plugged on a Stereopi) with balenaOS 2.83.21+rev1 (it looks like the driver has been dropped many version earlier tho)

I replaced it with a TP-Link WN725N which works as client but not as AP.
Then replaced it again with a Anadol (ralink) which seems to work well.

Wifi-connect readme privided some information as well (but I found it too late) : https://github.com/balena-os/wifi-connect#supported-boards--dongles