Broken docker link in "Building the OpenXR Specification" page

[dgough]

The URL to the docker file in Building the OpenXR Specification is broken. I assume it is supposed to be:

https://github.com/KhronosGroup/DockerContainers/blob/main/openxr-sdk.Dockerfile

Also, the instructions mention open-in-docker.sh, but I don't see that anywhere.