add a hint for degoogled devices

[viktoriasee]

You write in the readme that there will be limitations with Google Play Services. For long this has been the only way. But nowadays there is the Authnkey project which has state of the art support and also works on degoogled devices. May be worth noting.

[BryanJacobs]

Both Authnkey and MicroG support FIDO2 authenticators well (MicroG as of microg/GmsCore#2194 ).. I think mentioning MicroG as an alternative to Google Play Services is probably enough of a "hint". There are other software packages out there too, but I don't think this is the place for a comprehensive list.

Nothing against Authnkey, it's good stuff, but this repo is an authenticator not a whole ecosystem. The important point is that the applet isn't broken just because you tried to use it with Play Services and Play Services does strange things.