Update README.md

Author: nicolas-van

README.md

@@ -57,3 +57,17 @@ You must also choose a theme:
 That's it! Now you can juste use the link provided by Github to access you website:
 
 ![](./printscreen4.png)
+
+## Usage guide
+
+* Any markdown file in your repository will display in your Github Pages website. You just have to use the same path to access it and replace the `.md` extension by `.html`.
+* To make links between your Markdown files just use a relative path to the other Markdown file. The configuration you copy pasted in your `_config.yml` provides a plugin to convert those URLs. So your Markdown files will have correct links both in Github and Github Pages.
+* You should be able to use any [Github Flavored Markdown](https://guides.github.com/features/mastering-markdown/).
+
+## Contributing
+
+See the [Contribution Guide](./CONTRIBUTING.md).
+
+## License
+
+See the [License File](./LICENSE.md).