FIDO2: describe W10 AD-based login

[szszszsz]

Describe AD-based login on W10 using FIDO2. Example articles:

• https://docs.microsoft.com/en-us/azure/active-directory/authentication/howto-authentication-passwordless-security-key#requirements
• https://techcommunity.microsoft.com/t5/core-infrastructure-and-security/how-to-password-less-fido2-security-key-sign-in-to-windows-10/ba-p/1434583
• https://support.nitrokey.com/t/nitrokey-fido2-azure-ad/2078/3?u=szszszsz