Update README.md

Author: SajjadPourali

README.md

@@ -2,7 +2,6 @@ IpStack
 =======
 
 An asynchronous lightweight userspace implementation of TCP/IP stack for Tun device.
-Unstable, under development.
 
 [![Crates.io](https://img.shields.io/crates/v/ipstack.svg)](https://crates.io/crates/ipstack)
 [![ipstack](https://docs.rs/ipstack/badge.svg)](https://docs.rs/ipstack)