Improve the readme

Author: sylvestre

README.md

@@ -2,4 +2,17 @@
 
 [![Task Status](https://community-tc.services.mozilla.com/api/github/v1/repository/mozilla/rust-code-analysis/master/badge.svg)](https://community-tc.services.mozilla.com/api/github/v1/repository/mozilla/rust-code-analysis/master/latest)
 
-The goal of this project is to be able to analyse Rust source code.
+This project is a Rust crate (library) to analyse source code. This software is based on [Tree Sitter](https://github.com/tree-sitter/tree-sitter).
+
+It supports several languages:
+* C++
+* C#
+* CSS
+* Go
+* HTML
+* Java
+* JavaScript
+* The JavaScript used in Firefox internal
+* Python
+* Rust
+* Typescript