add badges for crates.io and docs.rs (dragoon/komodo!179)

this MR adds two new badges to the README
- the crate (links to the [Komodo crate](https://crates.io/crates/komodo))
- the documentation (links to the [doc](https://docs.rs/komodo/latest/komodo/))

README.md

 # Komodo: Cryptographically-proven Erasure Coding
 
 [![release](https://gitlab.isae-supaero.fr/dragoon/komodo/-/badges/release.svg)](https://gitlab.isae-supaero.fr/dragoon/komodo/-/releases)
+[![crate](https://img.shields.io/crates/v/komodo)](https://crates.io/crates/komodo)
+[![docs](https://img.shields.io/docsrs/komodo)](https://docs.rs/komodo/latest/komodo/)
 [![source](https://gitlab.isae-supaero.fr/dragoon/komodo/badges/main/pipeline.svg?key_text=GitLab%20CI)](https://gitlab.isae-supaero.fr/dragoon/komodo/-/pipelines)
 [![mirror](https://github.com/dragoon-rs/komodo/actions/workflows/ci.yml/badge.svg)](https://github.com/dragoon-rs/komodo/actions)