Merge pull request #357 from venth/update_readme_passcode

Document supported Duo authentication methods better

README.md

@@ -16,7 +16,11 @@ The project provides command line tool - `aws-adfs` to ease AWS cli authenticati
 ### MFA integration
 
 aws-adfs integrates with:
-* [duo security](https://duo.com) MFA provider with support for FIDO U2F (CTAP1) / FIDO2 (CTAP2) hardware authenticators
+* [duo security](https://duo.com) MFA provider with support for:
+  * Duo mobile application push (verified by code or not) using the `Duo Push` authentication method.
+  * Phone call using the `Phone Call` authentication method.
+  * OTP 6 digit codes generated by Duo Mobile application, and hardware tokens (e.g. RSA or Yubikey) using the `Passcode` authentication method.
+  * FIDO U2F (CTAP1) / FIDO2 (CTAP2) hardware authenticators using the `WebAuthn Security Key` authentication method.
 * [Symantec VIP](https://vip.symantec.com/) MFA provider
 * [RSA SecurID](https://www.rsa.com/) MFA provider