Tweak the README

README.md

@@ -2,6 +2,7 @@
 
 <a href="https://travis-ci.org/tsileo/little-boxes"><img src="https://travis-ci.org/tsileo/little-boxes.svg?branch=master" alt="Build Status"></a>
 <a href="https://codecov.io/gh/tsileo/little-boxes"><img src="https://codecov.io/gh/tsileo/little-boxes/branch/master/graph/badge.svg" /></a>
+<img src="https://img.shields.io/pypi/pyversions/little-boxes.svg" />
 <a href="https://github.com/tsileo/little-boxes/blob/master/LICENSE"><img src="https://img.shields.io/badge/license-ISC-blue.svg?style=flat" alt="License"></a>
 
 Tiny [ActivityPub](https://activitypub.rocks/) framework written in Python, both database and server agnostic.