update faq for getting nodegroup's userdata and launch templates

[ilyesAj]

Description

When an EKS cluster is created using eksctl , it seems like the launch template created in the cloud formation stack is not used .
When the cluster bootstraps, the AWSServiceRoleForAmazonEKSNodegroup will create a launch template on your behalf and will be used for the ASG attached to the nodeGroup . This launch template will have the required userdata .

Checklist

• Added tests that cover your change (if possible)
• Added/modified documentation as required (such as the README.md, or the userdocs directory)
• Manually tested
• Made sure the title of the PR is a good description that can go into the release notes
• (Core team) Added labels for change area (e.g. area/nodegroup) and kind (e.g. kind/improvement)

BONUS POINTS checklist: complete for good vibes and maybe prizes?! 🤯

• Backfilled missing tests for code in same general area 🎉
• Refactored something and made the world a better place 🌟

[github-actions]

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