keccak: add README.md (#12)

Adds a basic README to the crate

keccak/Cargo.toml

@@ -8,6 +8,7 @@ documentation = "https://docs.rs/keccak"
 repository = "https://github.com/RustCrypto/sponges"
 keywords = ["crypto", "sponge", "keccak", "keccak-f", "keccak-p"]
 categories = ["cryptography", "no-std"]
+readme = "README.md"
 
 [dependencies]
 packed_simd = { version = "0.3.7", package = "packed_simd_2", optional = true }

keccak/README.md

@@ -0,0 +1,56 @@
+# RustCrypto: Keccak Sponge Function
+
+[![crate][crate-image]][crate-link]
+[![Docs][docs-image]][docs-link]
+[![Build Status][build-image]][build-link]
+![Apache2/MIT licensed][license-image]
+![Rust Version][rustc-image]
+[![Project Chat][chat-image]][chat-link]
+
+Pure Rust implementation of the [Keccak Sponge Function][1].
+
+[Documentation][docs-link]
+
+## Minimum Supported Rust Version
+
+Rust **1.41** or higher.
+
+Minimum supported Rust version can be changed in the future, but it will be
+done with a minor version bump.
+
+## SemVer Policy
+
+- All on-by-default features of this library are covered by SemVer
+- MSRV is considered exempt from SemVer as noted above
+
+## License
+
+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)
+
+[crate-image]: https://img.shields.io/crates/v/keccak.svg
+[crate-link]: https://crates.io/crates/keccak
+[docs-image]: https://docs.rs/keccak/badge.svg
+[docs-link]: https://docs.rs/keccak/
+[license-image]: https://img.shields.io/badge/license-Apache2.0/MIT-blue.svg
+[rustc-image]: https://img.shields.io/badge/rustc-1.41+-blue.svg
+[chat-image]: https://img.shields.io/badge/zulip-join_chat-blue.svg
+[chat-link]: https://rustcrypto.zulipchat.com/#narrow/stream/260041-hashes
+[build-image]: https://github.com/RustCrypto/sponges/actions/workflows/keccak.yml/badge.svg
+[build-link]: https://github.com/RustCrypto/sponges/actions/workflows/keccak.yml
+
+[//]: # (general links)
+
+[1]: https://keccak.team/keccak.html