docs: update nightshade crate README to mention dual licensing

- Add MIT and Apache 2.0 dual license information
- Match licensing format from workspace README
- Include contributor license agreement section

Author: matthewjberger

crates/nightshade/README.md

@@ -60,4 +60,13 @@ WebGPU is supported in:
 
 ## License
 
-This project is licensed under the MIT License - see the [LICENSE](https://github.com/matthewjberger/nightshade/blob/main/LICENSE.md) file for details.
+Nightshade is free, open source and permissively licensed! All code in this repository is dual-licensed under either:
+
+* MIT License ([LICENSE-MIT](https://github.com/matthewjberger/nightshade/blob/main/LICENSE-MIT) or http://opensource.org/licenses/MIT)
+* Apache License, Version 2.0 ([LICENSE-APACHE](https://github.com/matthewjberger/nightshade/blob/main/LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
+
+at your option. This means you can select the license you prefer! This dual-licensing approach is the de-facto standard in the Rust ecosystem.
+
+### 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.