[DOC] - Document minimal AWS IAM policies required for deploying and destroying Nebari

[marcelovilla]

Preliminary Checks

• This issue is not a question, feature request, RFC, or anything other than a bug report. Please post those things in GitHub Discussions: https://github.com/nebari-dev/nebari/discussions

Summary

Currently, our docs suggest attaching the AdministratorAccess policy to the IAM users that will need to deploy and destroy Nebari (see this and this).

While this simplifies the setup, it's far from ideal from a security and principle-of-least-privilege standpoint.

We should define and document minimal IAM policies required to deploy and destroy a Nebari cluster on AWS. This will help users follow best practices and safely integrate Nebari into more restrictive cloud environments.