You are familiar with README files like this one. This file format is markdown. See the .md file extension name.

It is not just GitHub default files - like README, CONTRIBUTING, LICENSE - that are in the .md format, any files can be that format.

As you know, when there is a file called README.md in a repository that file is displayed below the list of files and folders in the repoistory. This is the case also for any other folder than the top folder. You can have a README.md in, for example, the BASELINE folder that gives instructions on what is going in that folder and how those files are inteded to be used.

Click the example folder to see the two files in markdown format there.