update binding genator home page

Author: Mihail Slavchev

binding-generator/README.md

@@ -1,2 +1,40 @@
 # android-binding-generator
-Contains the source of the binding generator tool for the NativeScript's Android Runtime.
+
+This project is used in the [NativeScript runtime for Android](https://github.com/NativeScript/android-runtime) to generate Java subclasses at runtime. Supppose you have the following Java class
+
+```Java
+package com.example;
+
+public class MyClass {
+   public int add(int x, int y) {
+      return x + y;
+   }
+}
+```
+
+In NativeScript, you can inherit from `MyClass` using the following syntax:
+
+```JavaScript
+var MyNewClass = com.example.MyClass.extend({
+   add: function(x, y) {
+      return x * y;
+   }
+})
+
+var obj = new MyNewClass();
+```
+
+Using `extend` function will create a new Java class that looks roughly as follows
+```Java
+package <some auto-generated package name>;
+
+public <some auto-generated class name> extends com.example.MyClass {
+   public int add(int x, int y) {
+      java.lang.Object[] params = new Object[2];
+      params[0] = x;
+      params[1] = y;
+      return (int)com.tns.Platform.callJSMethod(this, "add", int.class, params);
+   }
+}
+```
+The binding generator uses [ASMDEX library](http://asm.ow2.org/asmdex-index.html) to create the class above and to produce the corresponding `*.dex` file.