README.md: flesh out with some real content (#37)

- Adds "About", "Crates", "License" and "Contribution" sections
- Adds badges and links

Author: tarcieri

README.md

@@ -1,2 +1,42 @@
-# KEMs
-Collection of Key Encapsulation Mechanisms written in pure Rust
+# [RustCrypto]: Key Encapsulation Mechanisms (KEMs) [![Project Chat][chat-image]][chat-link] [![dependency status][deps-image]][deps-link]
+
+Collection of [Key Encapsulation Mechanisms] (KEMs) written in pure Rust.
+
+# About
+
+KEMs are public-key algorithms designed to secure symmetric key material for transmission, and are 
+commonly used in transport encryption protocols (e.g. [TLS]) and hybrid cryptosystems (e.g. [HPKE]).
+
+## Crates
+
+| Name     | crates.io                                                                                   | Docs                                                                         | Description        |
+|----------|---------------------------------------------------------------------------------------------|------------------------------------------------------------------------------|--------------------|
+| `dhkem`  | [![crates.io](https://img.shields.io/crates/v/dhkem.svg)](https://crates.io/crates/dhkem)   | [![Documentation](https://docs.rs/dhkem/badge.svg)](https://docs.rs/dhkem)   | Diffie-Hellman KEM |
+| `ml-kem` | [![crates.io](https://img.shields.io/crates/v/ml-kem.svg)](https://crates.io/crates/ml-kem) | [![Documentation](https://docs.rs/ml-kem/badge.svg)](https://docs.rs/ml-kem) | Module Lattice KEM |
+
+## License
+
+All crates licensed under either of
+
+- [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0)
+- [MIT license](http://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.
+
+[//]: # "badges"
+[chat-image]: https://img.shields.io/badge/zulip-join_chat-blue.svg
+[chat-link]: https://rustcrypto.zulipchat.com/#narrow/stream/406484-KEMs
+[deps-image]: https://deps.rs/repo/github/RustCrypto/KEMs/status.svg
+[deps-link]: https://deps.rs/repo/github/RustCrypto/KEMs
+
+[//]: # "links"
+[RustCrypto]: https://github.com/RustCrypto/
+[Key Encapsulation Mechanisms]: https://en.wikipedia.org/wiki/Key_encapsulation_mechanism
+[TLS]: https://en.wikipedia.org/wiki/Transport_Layer_Security
+[HPKE]: https://datatracker.ietf.org/doc/rfc9180/