Need to remove windows-10-byol from docs

[WestonThayer]

https://github.com/GoogleCloudPlatform/compute-image-tools/releases/tag/v20191206 removed the windows-10-byol os type, and added windows-10-x64-byol and windows-10-x86-byol. But the docs haven't been updated.

Likewise, gcloud compute images import needs to be updated.

[WestonThayer]

Since gcloud compute images import won't accept --os windows-10-x64-byol, you can work around it for now by creating a cloudbuilld YAML file:

steps:
  - name: gcr.io/compute-image-tools/gce_vm_image_import:release
    args:
      [
        "-source_file=...",
        "-os=windows-10-x64-byol",
      ]

Then gcloud builds submit --config=above.yaml --no-source.

[rofuentes]

gcloud SDK will have the new os types in the 273.0.0 release scheduled for 2019-12-10. Documentation PR is forthcoming.