Update documentation on node initialization taints

[UtheMan]

Clarified details about node initialization taints, including their lifecycle and visibility on nodes after updates.

[prmerger-automator]

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[Copilot]

Pull Request Overview

This PR updates the documentation for node initialization taints in AKS to provide clearer information about their lifecycle and visibility, specifically addressing when these taints become visible on nodes.

• Clarified the behavior of node initialization taints during scaling and upgrade operations
• Added important notes about VMSS model updates and when taints become visible on nodes
• Improved the explanation of taint lifecycle management

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[Copilot]

[nitpick] This important note contains repetitive information about VMSS model updates. The last two sentences essentially convey the same information and could be consolidated for clarity.

Suggested change

> When updating a cluster with a node initialization taint, the taints apply to all node pools in the cluster. If your nodes are using VMSS, you can view updates to node initialization taints on the node after the node's VMSS model is updated (for example, after a node image version upgrade operation). Initialization taints will not appear on your nodes until an operation that triggers a VMSS model update occurs.

> When updating a cluster with a node initialization taint, the taints apply to all node pools in the cluster. For nodes using VMSS, initialization taints will appear only after an operation that triggers a VMSS model update (such as a node image version upgrade).

[ShannonLeavitt]

@allyford

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