feat(doc): add license section to README and update badges

Author: luisschwab

README.md

@@ -1,15 +1,31 @@
-# rust-electrum-client 
-[![Build Status]][GitHub Workflow] [![Latest Version]][crates.io] [![MSRV Badge]][Rust Blog]
+# rust-electrum-client
 
-[Build Status]: https://github.com/bitcoindevkit/rust-electrum-client/actions/workflows/cont_integration.yml/badge.svg
-[GitHub Workflow]: https://github.com/bitcoindevkit/rust-electrum-client/actions?query=workflow%3ACI
-[Latest Version]: https://img.shields.io/crates/v/electrum-client.svg
-[crates.io]: https://crates.io/crates/electrum-client
-[MSRV Badge]: https://img.shields.io/badge/rustc-1.75.0%2B-lightgrey.svg
-[Rust Blog]: https://blog.rust-lang.org/2023/12/28/Rust-1.75.0.html
+<p>
+    <a href="https://crates.io/crates/electrum-client"><img src="https://img.shields.io/crates/v/electrum-client.svg"/></a>
+    <a href="https://docs.rs/electrum-clien"><img src="https://img.shields.io/badge/docs.rs-electrum--client-blue"/></a>
+    <a href="https://https://blog.rust-lang.org/2023/12/28/Rust-1.75.0.html"><img src="https://img.shields.io/badge/MSRV-1.75.0%2B-orange.svg"/></a>
+    <a href="https://github.com/bitcoindevkit/rust-electrum-client/blob/master/LICENSE.md"><img src="https://img.shields.io/badge/License-MIT%2FApache--2.0-red.svg"/></a>
+    <a href="https://github.com/bitcoindevkit/rust-electrum-client/actions/workflows/cont_integration.yml"><img src="https://github.com/bitcoindevkit/rust-electrum-client/actions/workflows/cont_integration.yml/badge.svg"></a>
+</p>
 
 Bitcoin Electrum client library. Supports plaintext, TLS and Onion servers.
 
 ## Minimum Supported Rust Version (MSRV)
 
 This library should compile with any combination of features with Rust 1.75.0.
+
+## License
+
+Licensed under either of
+
+* Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or <https://www.apache.org/licenses/LICENSE-2.0>)
+* MIT license ([LICENSE-MIT](LICENSE-MIT) or <https://opensource.org/licenses/MIT>)
+
+at your option.
+
+### 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.