Add link to lovr-android-builder;

guides/Compiling.md

@@ -113,7 +113,10 @@ the command:
 Android
 ---
 
-Here be dragons.
+To compile an Android APK with CMake, follow the steps below.
+
+There is also a [`lovr-android-builder`](https://github.com/Udinanon/lovr-android-builder) project
+that builds the APK in a Docker container, automating most of the process.
 
 ### Setup