Issue 4105 - [build] Make it possible to build arbitrary ABB revisions

abb-build/README.md

+Adblock Browser Build Automation
+================================
+
+Build automation for Adblock Browser for Android.
+
+Getting/updating the dependencies
+---------------------------------
+
+This repository has dependencies that aren't part of this repository. They are
+retrieved and updated during the build process, but you can also manually update
+them by running the following:
+
+    ./ensure_dependencies.py
+
+Creating a build
+----------------
+
+### Configuration
+
+First, create a `config.py` file:
+
+    cp config.py.sample config.py
+
+Then modify it for your system.
+
+### Building
+
+Builds are generated using the `build.py` script, just run it without parameters
+to learn how to use it.