Document issue when switching from EDDSA to non EDDSA firmware

[Lab-8916100448256]

We need to document our findings regarding the issues that occurs when switching from EDDSA to non EDDSA firmware into the troubleshooting section of the wiki.

Here is a test I just did : 
Flash a virgin raspberry pico2 with [pico-fido-pico2.uf2](https://github.com/librekeys/pico-fido-firmwares/releases/download/picofido-7.4.2-librekeys%2B1/pico-fido-pico2.uf2)
2.Test unlock storage => OK
Flash [pico-fido-pico2-eddsa.uf2](https://github.com/librekeys/pico-fido-firmwares/releases/download/picofido-7.4.2-librekeys%2B1/pico-fido-pico2-eddsa.uf2) onto it
Use https://webauthn.io/ to create a sign-in data onto the key.
Test unlock storage => OK
Flash back [pico-fido-pico2.uf2](https://github.com/librekeys/pico-fido-firmwares/releases/download/picofido-7.4.2-librekeys%2B1/pico-fido-pico2.uf2)
Test unlock storage => Error
...
I've made more tests with EDDSA and non EDDSA firmwares which confirm this.
unlocking storage fails with non EDDSA firmware if the key contains a passkey that was created with EDDSA firmware. It is possible to switch from EDDSA to non EDDSA firmware if all passkeys (and probably also ssh keys) that were created with EDDSA firmware are deleted before flashing non EDDSA firmware. Another option it to completely reset the key after having flashed non EDDSA firmware using Chrome, wich deletes everything on the key and also reset the PIN.