When you publish something open source, one of the greatest motivations is that anyone can just jump in and start contributing to your project:
"If you'd like to contribute, please fork the repository and use a feature branch. Pull requests are warmly welcome."
If there's anything else that a developer needs to know (e.g. the code style
guide), you should link it here. If there's a lot of things to take into
consideration, it is common to separate this section to its own file called
CONTRIBUTING.md (or similar).
"Give Credit where its Due": Credit goes to all the original repo owners, contributors, and author into making this project. (If possible, please provide the GitHub URLs and names to all that contributed including the project owner)