Update README.md

README.md

@@ -1,9 +1,11 @@
 picotls
 ===
 
-Picotls is a TLS 1.3 implementation written in C.
+Picotls is a [TLS 1.3](https://tlswg.github.io/tls13-spec/) implementation written in C.
 
-The primary goal of the project is to create a tiny but fast TLS 1.3 implementation that can be used with the HTTP/2 protocol stack and possibly the upcoming QUIC stack of the [H2O HTTP/2 server](https://h2o.examp1e.net).
+At the moment, the library implements Draft 16 of the specification (1-RTT ECDH + server-certificate + AES128-GCM only).
+
+Primary goal of the project is to create a fast, tiny TLS 1.3 implementation that can be used with the HTTP/2 protocol stack and possibly the upcoming QUIC stack of the [H2O HTTP/2 server](https://h2o.examp1e.net).
 
 The library only implements the communication protocol.
 Cryptographic operations are delegated to OpenSSL using callbacks.