Centralize license and MSRV boilerplate into the repo readme.

embassy-executor-macros/README.md

@@ -3,13 +3,3 @@
 An [Embassy](https://embassy.dev) project.
 
 NOTE: Do not use this crate directly. The macros are re-exported by `embassy-executor`.
-
-## License
-
-This work is licensed under either of
-
-- Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or
-  <http://www.apache.org/licenses/LICENSE-2.0>)
-- MIT license ([LICENSE-MIT](LICENSE-MIT) or <http://opensource.org/licenses/MIT>)
-
-at your option.