android build: add "how to deploy apk on phone" to readme

electrum/gui/kivy/Readme.md

@@ -55,6 +55,14 @@ folder.
 You probably need to clear the cache: `rm -rf .buildozer/android/platform/build/{build,dists}`
 
 
+### How do I deploy on connected phone for quick testing?
+Assuming `adb` is installed:
+```
+$ adb -d install -r bin/Electrum-*-debug.apk
+$ adb shell monkey -p org.electrum.electrum 1
+```
+
+
 ### How do I get an interactive shell inside docker?
 ```
 $ sudo docker run -it --rm \