add challenges-and-prizes license to Challenge_gov

LICENSE

@@ -1,10 +1,32 @@
+# License
+
+As a work of the [United States government](https://www.usa.gov/), this project is in the public domain within the United States of America.
+
+Additionally, we waive copyright and related rights in the work worldwide through the CC0 1.0 Universal public domain dedication.
+
+## CC0 1.0 Universal Summary
+
+This is a human-readable summary of the [Legal Code (read the full text)](https://creativecommons.org/publicdomain/zero/1.0/legalcode).
+
+### No Copyright
+
+The person who associated a work with this deed has dedicated the work to the public domain by waiving all of their rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
+
+You can copy, modify, distribute, and perform the work, even for commercial purposes, all without asking permission.
+
+### Other Information
+
+In no way are the patent or trademark rights of any person affected by CC0, nor are the rights that other persons may have in the work or in how the work is used, such as publicity or privacy rights.
+
+Unless expressly stated otherwise, the person who associated a work with this deed makes no warranties about the work, and disclaims liability for all uses of the work, to the fullest extent permitted by applicable law. When using or citing the work, you should not imply endorsement by the author or the affirmer.
+
+# Media Usage Guidelines
 Materials created by the federal government are generally part of the public domain and may be used, reproduced, and distributed without permission. However, such materials may not be used in a manner that implies any affiliation or endorsement by the U.S government, GSA or GSA employees of your company, product, service, website, or publication.
 
 GSA video, audio, photographs, and text material can be used for educational or informational purposes, including news media, photo collections, textbooks, public exhibits, and Internet web pages.
 
 Certain GSA and GSA affiliated seals, logos, and insignia are the protected property of the federal government and may not be used without our prior permission. Other images, text, terms, phrases, slogans and/or designs appearing on our websites also may be the trademarked property of others, used by GSA under a license. Prior to using such a trademark, it is your responsibility to acquire any necessary permission from the owner(s) of the trademark.
 
-
 Unless a copyright is indicated, information on the General Services Administration’s websites is in the public domain and may be copied, downloaded, and distributed without permission. Citation of GSA as the source of the information is recommended and appreciated.
 
 Preferable credit lines accompanying GSA material are thus: GSA Photo, GSA Video, originally published by GSA.gov, etc.