fix image size badge

Author: jpillora

README.md

@@ -41,7 +41,7 @@ See [the latest release](https://github.com/jpillora/chisel/releases/latest) or
 
 ### Docker
 
-[![Docker Pulls](https://img.shields.io/docker/pulls/jpillora/chisel.svg)](https://hub.docker.com/r/jpillora/chisel/) [![Image Size](https://images.microbadger.com/badges/image/jpillora/chisel.svg)](https://microbadger.com/images/jpillora/chisel)
+[![Docker Pulls](https://img.shields.io/docker/pulls/jpillora/chisel.svg)](https://hub.docker.com/r/jpillora/chisel/) [![Image Size](https://img.shields.io/docker/image-size/jpillora/chisel/latest)](https://microbadger.com/images/jpillora/chisel)
 
 ```sh
 docker run --rm -it jpillora/chisel --help
@@ -406,4 +406,4 @@ Since WebSockets support is required:
 
 ## License
 
-[MIT](https://github.com/jpillora/chisel/blob/master/LICENSE) © Jaime Pillora
+[MIT](https://github.com/jpillora/chisel/blob/master/LICENSE) © Jaime Pillora