Add readme for building an Android APK

android/README.md

@@ -0,0 +1,23 @@
+System Requirements
+
+* Download [Android SDK](http://developer.android.com/sdk/index.html)
+* Download [Crosswalk](https://crosswalk-project.org/#documentation/getting_started/linux_host_setup) and setup the environment
+
+Add to your ~/.bash_profile or ~/.bashrc
+
+```
+export CROSSWALK="<path to Crosswalk directory>"
+```
+
+To build the APK run the script:
+
+```
+sh android/build.sh
+```
+
+To install the APK in your device run:
+
+```
+adb install -r Copay_VERSION_arm.apk
+```
+