Updating the registry XML

In order to update the registry XML files and retain the history you cannot simply download the files the Khronos website and copy them into this directory. You should follow these steps, instead:

1. check out the khronos-registry branch
2. download the XML files from the Khronos repository
3. copy them under the registry directory
4. check the result for consistency and commit it
5. check out the master branch and merge the khronos-registry branch into it with the appropriate commit message