Add link to releases in README

Fix #1460. The original change is dismissed because of usage of possibly copyrighted material.

README.md

@@ -1,7 +1,6 @@
 ## Shadowsocks for Android
 
-A [shadowsocks](http://shadowsocks.org) client for Android, written in Scala.
-
+A [shadowsocks](http://shadowsocks.org) client for Android, written in Scala. [Get latest apk here](https://github.com/shadowsocks/shadowsocks-android/releases) or
 <a href="https://play.google.com/store/apps/details?id=com.github.shadowsocks"><img src="https://play.google.com/intl/en_us/badges/images/generic/en-play-badge.png" height="48"></a>
 
 ### CI STATUS