multi-cluster: add pre-install steps for kind

[jewertow]

Description

The ambient multi-cluster guide currently lacks instructions for users who want to test the setup locally with kind clusters.

Reviewers

• Ambient
• Docs
• Installation
• Networking
• Performance and Scalability
• Extensions and Telemetry
• Security
• Test and Release
• User Experience
• Developer Infrastructure
• Localization/Translation

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