add openfga (#5223)

README.md

@@ -250,6 +250,7 @@ _Libraries for implementing authentication schemes._
 - [loginsrv](https://github.com/tarent/loginsrv) - JWT login microservice with pluggable backends such as OAuth2 (Github), htpasswd, osiam.
 - [oauth2](https://github.com/golang/oauth2) - Successor of goauth2. Generic OAuth 2.0 package that comes with JWT, Google APIs, Compute Engine, and App Engine support.
 - [oidc](https://github.com/zitadel/oidc) - Easy to use OpenID Connect client and server library written for Go and certified by the OpenID Foundation
+- [openfga](https://github.com/openfga/openfga) - Implementation of fine-grained authorization based on the "Zanzibar: Google's Consistent, Global Authorization System" paper. Backed by [CNCF](https://www.cncf.io/).
 - [osin](https://github.com/openshift/osin) - Golang OAuth2 server library.
 - [otpgen](https://github.com/grijul/otpgen) - Library to generate TOTP/HOTP codes.
 - [otpgo](https://github.com/jltorresm/otpgo) - Time-Based One-Time Password (TOTP) and HMAC-Based One-Time Password (HOTP) library for Go.