Update aws notebooks

[albertodepaola]

Updating notebooks to llama 3 when possible.

Removing the AWS specific notebook on prompting Llama 2, moving to the quick started guide and leaving it as the only prompt eng guide. We need to create a net new one for Llama 3 and keep this one for reference on Llama 2.

Feature/Issue validation/testing

Running the notebooks and checking in the outputs for every cell.

Before submitting

• [ ] This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
• [x] Did you read the contributor guideline, Pull Request section?
• [ ] Was this discussed/approved via a Github issue? Please add a link to it if that's the case.
• [x] Did you make sure to update the documentation with your changes?
• [ ] Did you write any new necessary tests?

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