What's a README? A README file broadly contains information about other files in a directory. It is usually in a plain text format, like markdown (.md) or text (.txt). It typically contains:
TITLE/SUMMARY: What does your project do? How is it used?
AUTHORS: Credit the people working on the project :)
GETTING STARTED: installation & dependency instructions
LICENSE: copyright and licensing info
CONTRIBUTING: guide for people who might want to contribute to the project
THANKS: acknowledge those who made it possible!