This is a folder with some useful notebooks, all the notebooks have a markdown file with the same name (or a README.md if its a single notebook folder) explaining what they do.
Contributing to notebooks and making new notebooks is very welcome. If you do so, make sure to make a markdown (.md) file to go with your notebook, it makes it easier for people to know what your notebook is about.
Check out the example notebook for a reference example you can use as a starting point.