[DOC] - Add user personas to docs

[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

We have a set of user personas that we put together a while back but they never made it onto the public docs. These would be helpful for some folks when identifying potential users, or designing usability studies, etc.

Steps to Resolve this Issue

Copy the user personas from notion into public docs.

[kcpevey]

@pavithraes where should these go in the docs?