docs: License to README

Author: laysakura

README.md

@@ -24,3 +24,13 @@ All you need to do are:
 #### Example application
 
 See [`c_example/`](https://github.com/SpringQL/SpringQL-client-c/tree/main/c_example) for how to write and build a SpringQL embedded application.
+
+## License
+
+Licensed under either of [Apache License, Version 2.0](LICENSE-APACHE) or [MIT license](LICENSE-MIT) at your option.
+
+Unless you explicitly state otherwise, any contribution intentionally submitted
+for inclusion in SpringQL by you, as defined in the Apache-2.0 license, shall be
+dual licensed as above, without any additional terms or conditions.
+
+Copyright (c) 2021 TOYOTA MOTOR CORPORATION.