Added mozilla badge

Author: whizsid

README.md

@@ -4,6 +4,7 @@
 
 <p align="center">
 <a href="https://opensource.org/licenses/MIT"><img src="https://img.shields.io/badge/License-MIT-brightgreen.svg" alt="License: MIT"></a>
+<a href="https://addons.mozilla.org/en-US/firefox/addon/rosy-number-translator/"> <img src="https://img.shields.io/amo/v/rosy-number-translator" alt="Rosy current version"/></a>
 </p>
 
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