README: mention the supported use cases (#48)

Author: marten-seemann

README.md

@@ -3,7 +3,13 @@
 [![PkgGoDev](https://pkg.go.dev/badge/github.com/quic-go/connect-ip-go)](https://pkg.go.dev/github.com/quic-go/connect-ip-go)
 [![Code Coverage](https://img.shields.io/codecov/c/github/quic-go/connect-ip-go/master.svg?style=flat-square)](https://codecov.io/gh/quic-go/connect-ip-go/)
 
-connect-ip-go is a partial implementation of the CONNECT-IP protocol [RFC 9484](https://datatracker.ietf.org/doc/html/rfc9484), based on [quic-go](https://github.com/quic-go/quic-go). It provides both a client and a proxy implementation.
+connect-ip-go is an implementation of the CONNECT-IP protocol [RFC 9484](https://datatracker.ietf.org/doc/html/rfc9484), allowing the proxying of IP packets in HTTP/3.
+
+It is based on [quic-go](https://github.com/quic-go/quic-go), and provides both a client and a proxy implementation.
+
+At this point, it supports the following use cases:
+* Remote Access VPN, see [Section 8.1 of RFC 9484](https://datatracker.ietf.org/doc/html/rfc9484#section-8.1)
+* Site-to-Site VPN, see [Section 8.2 of RFC 9484](https://datatracker.ietf.org/doc/html/rfc9484#section-8.2)
 
 
 ## Release Policy