Update demo.md

[niloysh]

What this PR does / why we need it:
Updates demo.md to introduce MTU parameter in NetworkAttachmentDefinition object. This fixes #264.

Special notes for your reviewer:

Release note:
NONE

[kubevirt-bot]

Hi @niloysh. Thanks for your PR.

I'm waiting for a k8snetworkplumbingwg member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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[phoracek]

Thanks for the patch @niloysh, would you please sign the commit, so we can merge it?

To do so, run git commit -s --amend and then force push again.

[phoracek]

/retest
/lgtm
/approve

[kubevirt-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: niloysh, phoracek

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

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• OWNERS [phoracek]

Approvers can indicate their approval by writing /approve in a comment
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[phoracek]

/release-note-none

[kubevirt-bot]

@niloysh: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-e2e-ovs-cni	2a11770	link	unknown	/test pull-e2e-ovs-cni

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository. I understand the commands that are listed here.