docs/BUILD.md: update instructions for Android build and deploy

Updated BUILD.md with up to date instructions for Android build and
deploy.

docs/BUILD.md

@@ -91,21 +91,32 @@ To create the installer, run the NSIS UI, then: compile NSI scripts -> frontend/
 
 ## Android
 
-EXPERIMENTAL / ALPHA, do not use in production.
-
+### Build
 Enter the Docker environment: `make dockerdev`
 
 Within the Docker dev environment, build the Android App: `make android`
 
-The Android Sdk is assumed to be in `/opt/android-sdk`. Use `make android ANDROID_SDK_ROOT=...` to
-use a different Sdk location.
-
 To update the app icon, execute `frontends/android/mkicon.sh`.
 The script isn't run during `make android` build.
 
 Build artifacts:
 * `frontends/android/BitBoxApp/app/build/outputs/apk/*`
 
+### Deploy
+Adb is required for the deploy, on GNU/Linux install `android-tools-adb`
+
+After connecting the device via USB, it is possible to verify the connection with `adb devices`
+
+Inside `frontends/android` folder: `make deploy-debug`
+
+### Deploy troubleshooting
+If the apk install goes wrong, here are some Android configuration that could help:
+* Enable developer options
+* Enable install via USB
+* Enable USB debugging
+* Set USB configuration to charge when the device is connected
+* Disable MIUI optimization and restart (for Xiaomi devices)
+
 ## Cross compile from GNU/Linux to Windows
 It is not currently possible to cross compile the BitBox wallet for Windows.
 The `qtwebwidgets` QT module only supports native building on Windows. It is