docs: Remove version restriction on IgvmNativeVpContextX64

[jethrogb]

The documentation mentions a file format version restriction for IgvmNativeVpContextX64. However, neither the generator nor the parser enforce this: they will happily generate/parse IGVM files with a IGVM_VHT_VP_CONTEXT header when the revision is 1 and the platform type is NATIVE. QEMU will happily launch such IGVMs correctly. As such, this entire restriction seems to be meaningless.

[chris-oo]

I disagree, this is a bug in the igvm crate as the parser should be enforcing this. Would you like to submit a fix for that instead?

[chris-oo]

If not, feel free to file an issue and I'll see if I can get to it next week. I suspect we aren't enforcing many v2 version requirements that we should be.

[jethrogb]

Changing the behavior now would break downstream.

[chris-oo]

I think we will need to change the behavior in the next version, because we cannot guarantee that this is stable which is the point of the unstable flag. Although, maybe we can relax it in this specific case, but let me think about that over the weekend.

[jethrogb]

The igvm crate doesn't have any features, and the igvm_c code also doesn't require any additional configuration to get the behavior described in the PR description.