[DOC] - Additional helm charts

[kcpevey]

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

Need to move docs on custom helm charts over to nebari (rename to additional helm charts).

https://github.com/nebari-dev/nebari/blob/d053784a80fb4d461a9c3f5dd324dce75e884ca2/docs/source/admin_guide/custom-helm-charts.md

Steps to Resolve this Issue

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[pavithraes]

I think this can be a section in the advanced settings doc where we cover about config.yaml in detail. We can add this after #115 is merged. :)