Welcome to the MDXEditor app. The content you see is a sandboxed working copy of the MDXEditor repository. You can play around with the app features and see how it works.
The repository that got checked out is a fork of the MDXEditor repository with the markdown documentation left in. You can toy around with the files present or create new ones to see how the app app works for you. Make sure to checkout ROADMAP.md for more details on what's the purpose and the future direction of the app.
The MDXEditor application is a cloud-based markdown editor for content stored in GitHub repositories. It allows you to author and edit markdown files in your own working copy, and then commit and push your changes back. The working copy is securely stored in the cloud, so you can access it from any device, without any need to do any setup or configuration locally.
The sandbox you're seeing is a client-side only version of the application, with push and pull operations disabled. You can still create and edit files, and see how the app works for you.