add license files and section in README

README.md

@@ -5,13 +5,31 @@ A crate for adding openxr support to Bevy ( planned to be upstreamed ).
 To see it in action run the example in `examples` with `cargo run --example xr`
 
 ## Discord
+
 Come hang out if you have questions or issues 
 https://discord.gg/sqMw7UJhNc
 
 ![](https://media.giphy.com/media/v1.Y2lkPTc5MGI3NjExY2FlOXJrOG1pbzFkYTVjZHIybndqamF1a2YwZHU3dXgyZGcwdmFzMiZlcD12MV9pbnRlcm5hbF9naWZfYnlfaWQmY3Q9Zw/CHbQyXOT5yZZ1VQRh7/giphy-downsized-large.gif)
 ![](https://media.giphy.com/media/v1.Y2lkPTc5MGI3NjExbHVmZXc2b3VhcGE2eHE2c2Y3NDR6cXNibHdjNjk5MmtyOHlkMXkwZyZlcD12MV9pbnRlcm5hbF9naWZfYnlfaWQmY3Q9Zw/Hsvp5el2o7tzgOf9GQ/giphy-downsized-large.gif)
+
 ## Troubleshooting
 
 - Make sure, if you're on Linux, that you have the `openxr` package installed on your system.
 - I'm getting poor performance.
     - Like other bevy projects, make sure you're building in release (example: `cargo run --example xr --release`)
+
+## License
+
+Unless otherwise specified, all code in this repository is dual-licensed under
+either:
+
+- MIT License ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
+- Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
+
+at your option. This means you can select the license you prefer!
+
+### Your contributions
+
+Unless you explicitly state otherwise, any contribution intentionally submitted
+for inclusion in the work by you, as defined in the Apache-2.0 license, shall
+be dual licensed as above, without any additional terms or conditions.