update Cargo.toml for crate

Cargo.toml

@@ -5,6 +5,8 @@ authors = ["arnaucube "]
 edition = "2018"
 license = "GPL-3.0"
 description = "Poseidon hash implementation"
+repository = "https://github.com/arnaucube/poseidon-rs"
+readme = "README.md"
 
 [dependencies]
 num = "0.2.0"

README.md

@@ -1,4 +1,4 @@
-# poseidon-rs [![Build Status](https://travis-ci.org/arnaucube/poseidon-rs.svg?branch=master)](https://travis-ci.org/arnaucube/poseidon-rs)
+# poseidon-rs [![Crates.io](https://img.shields.io/crates/v/poseidon-rs.svg)](https://crates.io/crates/poseidon-rs) [![Build Status](https://travis-ci.org/arnaucube/poseidon-rs.svg?branch=master)](https://travis-ci.org/arnaucube/poseidon-rs)
 Poseidon hash implementation in Rust, a zkSNARK friendly hash function.
 
 https://eprint.iacr.org/2019/458.pdf