Merge pull request #4 from vot/v4.2.1

Add release 4.2.1

Author: vot

readme.md

@@ -15,6 +15,7 @@ There's also a [CLI downloader in Node.js available on npm](https://www.npmjs.co
 [![4.0](https://img.shields.io/github/downloads/vot/ffbinaries-prebuilt/v4.0/total.svg)](https://github.com/vot/ffbinaries-prebuilt/releases/tag/v4.0)
 [![4.1](https://img.shields.io/github/downloads/vot/ffbinaries-prebuilt/v4.1/total.svg)](https://github.com/vot/ffbinaries-prebuilt/releases/tag/v4.1)
 [![4.2](https://img.shields.io/github/downloads/vot/ffbinaries-prebuilt/v4.2/total.svg)](https://github.com/vot/ffbinaries-prebuilt/releases/tag/v4.2)
+[![4.2.1](https://img.shields.io/github/downloads/vot/ffbinaries-prebuilt/v4.2.1/total.svg)](https://github.com/vot/ffbinaries-prebuilt/releases/tag/v4.2.1)
 
 
 *Make sure to check which components are included in which release. Limited builds of ffplay are available for Linux + ffserver is not available at all for Windows.*