documentation: Added License to the README.md (facebook#4294)

* Adding License to the README.md

* Adding new license wording on README

* Update README.md

Author: thiagopaiva99

README.md

@@ -224,3 +224,7 @@ We are grateful to the authors of existing related projects for their ideas and
 * [@eanplatter](https://github.com/eanplatter)
 * [@insin](https://github.com/insin)
 * [@mxstbr](https://github.com/mxstbr)
+
+## License
+
+Create React App is open source software [licensed as MIT](https://github.com/facebook/create-react-app/blob/master/LICENSE).