update node-labeller docs to include machine types labels

[dasionov]

What this PR does / why we need it:
minor updates to the node-labeller docs in regards to the machine type labels that is being used since kubevirt/kubevirt#13690

Release note:

update node-labeller docs to include machine type labels

[kubevirt-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by:
Once this PR has been reviewed and has the lgtm label, please assign iholder101 for approval. For more information see the Code Review Process.

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these files:

• docs/compute/OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[dasionov]

/cc @Barakmor1

is this enough? or should i elaborate more about the fact the node-labeller is a must since the machine-type is automatically included in the node-selector

[Barakmor1]

/lgtm

Thank you!

[kubevirt-bot]

Pull requests that are marked with lgtm should receive a review
from an approver within 1 week.

After that period the bot marks them with the label needs-approver-review.

/label needs-approver-review