Improve MetacatUI installation & config docs for new contributors

[robyngit]

The current documentation for installing and configuring MetacatUI provides the minimum essential steps for getting set up. However, there is room for improvement in making it more accessible and informative for new contributors. By providing clearer, more detailed examples and guidance, we hope to facilitate a smoother onboarding experience for those new to the project.

Areas for Enhancement:

• Example configs: Add example configs to demonstrate how to configure MetacatUI to use the production themes that are shipped with the project (KNB, ADC, DataONE), as well as how to overwrite these configs to point to test nodes
• Better troubleshooting: Update the troubleshooting page to include FAQs and solutions based on community feedback and common issues encountered by new contributors.
• Make docs easier to find: Point to installation docs from the main README.md, CONTRIBUTING.md, and main page of the MetacatUI doc site. Consider adding a more general "Getting Started" page.
• ⭐️ Others as identified by the community ⭐️: If you are new to MetacatUI or once were, and have suggestions or contributions based on your setup experience, your input would be invaluable! Please feel free to share your ideas about improving our installation and configuration documentation.

[ianguerin]

Similar to bullet point 1, I would want a sample config.js file that has all the values (except personal Cesium/Google Maps keys) that I need to be able to run and view the app without errors. I ran into a lot of problems until I was pointed to adding a theme, metacatContext, d1CNBaseUrl, and baseUrl.

[yvonnesjy]

I found https://nceas.github.io/metacatui/install/local.html the most helpful in my case. Also maybe the trick of using an incognito window can be in a troubleshoot section?