Readme info pages
When you open up a project in the IDE, Codio will try to locate a file called readme.md in the root of the project. If it finds one and you have not opened the project beforehand, it will open and display it in ‘markdown’ mode.
If you select the README.md file from the file tree, it will be opened up for editing using markdown. You can switch between markdown, 'preview’ and you can run in SplitView mode as highlighted in the above image.
The readme.md file should be written in markdown format. Here are a couple of references for markdown