chore: add BSD license to README file

README.md

@@ -96,12 +96,10 @@ Contributions will licensed according to the project licenses (see below).
 
 ## License
 
-Licensed under either of
-* MIT license
-  ([LICENSE-MIT](LICENSE) 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.
+`dart_wot` is licensed under the 3-Clause BSD License.
+See the `LICENSE` file for more information.
+
+    SPDX-License-Identifier: BSD-3-Clause
 
 ## Note on Third-Party Code
 
@@ -112,8 +110,8 @@ Copyright (c) 2018 Contributors to the Eclipse Foundation
 ## Contribution
 
 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.
+for inclusion in the work by you, shall be licensed as above, without any additional
+terms or conditions.
 
 ## Maintainers