Remove link for "multi-version upgrades" from AMI upgrade docs (#653)

MVU are not supported so link was confusing, and link pointed to the
upgrade notes page anyways.

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Author: morgangauth

docs/admin/deploy/machine-images/aws-ami.mdx

@@ -177,7 +177,6 @@ Please take time to review the following before proceeding with the upgrades:
 - [Changelog](/CHANGELOG)
 - [Update policy](/admin/updates#update-policy)
 - [Update notes](/admin/updates/kubernetes)
-- [Multi-version upgrade procedure](/admin/updates/kubernetes#multi-version-upgrade-procedure)
 
 <Callout type="warning">Back up your volumes before each upgrade!</Callout>