feat: add OpenID Provider Authentication Policy Extension specs

README.md

@@ -190,6 +190,7 @@ Where to discover learning resources about OpenID Connect.
 - [Initiating User Registration via OpenID Connect](https://openid.net/specs/openid-connect-prompt-create-1_0.html) - Specifications for initiating user registration via OpenID Connect and create prompt.
 - [OpenID Connect Session Management](https://openid.net/specs/openid-connect-session-1_0.html) - Specifications about OpenID Connect session management.
 - [OpenID Connect Client-Initiated Backchannel Authentication Flow - Core 1.0](https://openid.net/specs/openid-client-initiated-backchannel-authentication-core-1_0.html) - Specifications for Client-Initiated Backchannel Authentication (CIBA) flow.
+- [OpenID Provider Authentication Policy Extension 1.0](https://openid.net/specs/openid-provider-authentication-policy-extension-1_0.html) - Specifications about a mechanism by which a Relying Party can request that particular authentication policies like multi-factor authentication be applied by the OpenID Provider.
 
 #### Draft