chore(doc): add badge to readme

Author: tottoto

README.md

@@ -1,5 +1,9 @@
 # hyper-util
 
+[![crates.io](https://img.shields.io/crates/v/hyper-util.svg)](https://crates.io/crates/hyper-util)
+[![Released API docs](https://docs.rs/hyper-util/badge.svg)](https://docs.rs/hyper-util)
+[![MIT licensed](https://img.shields.io/badge/license-MIT-blue.svg)](./LICENSE)
+
 A collection of utilities to do common things with [hyper](https://hyper.rs).
 
 ## License