docs: Update handling eviction requests

[orelmisan]

What this PR does

PR #11532 changed the behavior of the pod eviction webhook.

Update the document to align it with the implementation.

Add an example output of kubectl drain command.

Fixes #

Why we need it and why it was done in this way

The following tradeoffs were made:

The following alternatives were considered:

Links to places where the discussion took place:

Special notes for your reviewer

Checklist

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• Design: A design document was considered and is present (link) or not required
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• Upgrade: Impact of this change on upgrade flows was considered and addressed if required
• Testing: New code requires new unit tests. New features and bug fixes require at least on e2e test
• Documentation: A user-guide update was considered and is present (link) or not required. You want a user-guide update if it's a user facing feature / API change.
• Community: Announcement to kubevirt-dev was considered

Release note

None

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[aburdenthehand]

/cc @fossedihelm

[orelmisan]

@acardace could you please have a look?