doc: update invalid link (#176)

Author: gengjiawen

README.md

@@ -1,7 +1,7 @@
 ## Android Docker Image for react native
 ![Build Docker image](https://github.com/react-native-community/docker-android/workflows/Build%20Docker%20image/badge.svg)
 ![Publish](https://github.com/react-native-community/docker-android/workflows/Publish/badge.svg)
-[![Docker Pulls](https://img.shields.io/docker/pulls/reactnativecommunity/react-native-android.svg?maxAge=3600)](https://hub.docker.com/r/reactnativecommunity/react-native-android) 
+[![Docker Pulls](https://img.shields.io/docker/pulls/reactnativecommunity/react-native-android.svg)](https://hub.docker.com/r/reactnativecommunity/react-native-android) 
 
 
 ## Motivation