Update readme: Include info about 64 bit builds

README.md

@@ -9,13 +9,38 @@ Maybe you simply need to build for one architecture because of other reasons? Th
 
 # Usage
 Include this plugin in your config.xml:
-``` xml
+```xml
 <plugin name="cordova-build-architecture" spec="https://github.com/MBuchalik/cordova-build-architecture.git#v1.0.3" source="git" />
 ```
 
 By default, it will try to produce arm builds only. If you want to target x86, add the following preference:
-``` xml
+```xml
 <preference name="buildArchitecture" value="x86" />
 ```
 
+## Advanced configuration
+Crosswalk also allows you to generate 64 bit builds. This is usually done via a command line parameter, but also seems to be possible using the following preference:
+```xml
+<preference name="xwalk64bit" value="true" />
+```
+
+If you want to fetch the 64 bit arm build, simply use use
+```xml
+<preference name="buildArchitecture" value="arm64" />
+```
+For the 64 bit x86 build, you have to specify the following value:
+```xml
+<preference name="buildArchitecture" value="x86_64" />
+```
+
+## Summary
+The following values can be used in our ```buildArchitecture``` preference:
+
+| target platform | value | should the xwalk64bit preference be set (to true)? |
+| -------- | ----- | ----------------------------- |
+| arm      | arm   | :x: |
+| arm: 64 bit | arm64 | :white_check_mark: |
+| x86      | x86   | :x: |
+| x86: 64 bit | x86_64 | :white_check_mark: |
+
 **Please note that this plugin is experimental.**