[DOC] - add example configurations for each cloud

[dcmcand]

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

It would be good to have example configs of recommended nebari-config.yaml files for each cloud deployment. Ideally the base example would feature a small, medium, and large user instance size and a small and large gpu instance size. We could additionally either add comments to these examples to explain why certain choices were made or come up with other configurations for other scenarios (ex. low cost deploy, high availability deploy, etc)

Steps to Resolve this Issue

1. Write example config for AWS
2. Write example config for GCP
3. Write example config for Azure
   ...

[dcmcand]

Ideally we could then pull these configs into the nebari ci to ensure they run and are up to date