Updating the api level badge (2)

Author: Javernaut

README.md

@@ -1,6 +1,6 @@
 # MediaFile
 
-[![API](https://img.shields.io/badge/API-16%2B-brightgreen.svg?style=flat)](https://android-arsenal.com/api?level=21)
+[![API](https://img.shields.io/badge/API-21%2B-brightgreen.svg?style=flat)](https://android-arsenal.com/api?level=21)
 [![MIT license](http://img.shields.io/badge/license-MIT-blue.svg)](https://github.com/Javernaut/WhatTheCodec/blob/master/LICENSE.txt)
 [![Android Weekly #378](https://androidweekly.net/issues/issue-378/badge)](https://androidweekly.net/issues/issue-378)
 [![Android Weekly #396](https://androidweekly.net/issues/issue-396/badge)](https://androidweekly.net/issues/issue-396)