Add MIT license

README.md

@@ -254,6 +254,10 @@ Data/                    runtime state (created on first run, not committed): Da
                          Presence.json, Snapshots.json, Completed.json, Logs/
 ```
 
+## License
+
+USMT Dash is released under the [MIT License](LICENSE).
+
 ## Third-party code
 
 Vendored in `web/vendor/` under their own licenses: [marked](https://github.com/markedjs/marked)