Thanks for sharing your open source project, but it looks like you haven't specified a license.
When you make a creative work (which includes code), the work is under exclusive copyright by default. Unless you include a license that specifies otherwise, nobody else can use, copy, distribute, or modify your work without being at risk of take-downs, shake-downs, or litigation. Once the work has other contributors (each a copyright holder), “nobody” starts including you.
choosealicense.com is a great resource to learn about open source software licensing.