Update CI to Pharo12. Update README

README.md

@@ -4,13 +4,17 @@
 [![Coverage Status](https://coveralls.io/repos/github/pharo-ai/graph-algorithms/badge.svg?branch=master)](https://coveralls.io/github/pharo-ai/graph-algorithms?branch=master)
 [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg?style=flat-square)](http://makeapullrequest.com)
 [![Project Status: Active – The project has reached a stable, usable state and is being actively developed.](http://www.repostatus.org/badges/latest/active.svg)](http://www.repostatus.org/#active)
+[![Pharo version](https://img.shields.io/badge/Pharo-9-%23aac9ff.svg)](https://pharo.org/download)
+[![Pharo version](https://img.shields.io/badge/Pharo-10-%23aac9ff.svg)](https://pharo.org/download)
+[![Pharo version](https://img.shields.io/badge/Pharo-11-%23aac9ff.svg)](https://pharo.org/download)
+[![Pharo version](https://img.shields.io/badge/Pharo-12-%23aac9ff.svg)](https://pharo.org/download)
 [![license-badge](https://img.shields.io/badge/license-MIT-blue.svg)](https://img.shields.io/badge/license-MIT-blue.svg)
 
 For more information please refer to the pharo-ai wiki: https://github.com/pharo-ai/wiki/blob/master/wiki/Graphs/Graph-Algorithms.md
 
 Or also to our graphs booklet [Booklet-PharoGraphs](https://github.com/SquareBracketAssociates/Booklet-PharoGraphs)
 
-### Table of Contents
+## Table of Contents
 
 - [Description](#description)
 - [How to install it](#how-to-install-it)