docs: docs.rs link and install instructions

Author: claytonwramsey

README.md

@@ -2,6 +2,7 @@
 
 [![arXiv CAPT](https://img.shields.io/badge/arXiv-2406.02807-b31b1b.svg)](https://arxiv.org/abs/2406.02807)
 [![Crates.io page](https://img.shields.io/crates/v/capt)](https://crates.io/crates/capt)
+[![docs.rs](https://img.shields.io/docsrs/capt)](https://docs.rs/capt)
 
 ![Demo video](doc/capt_demo.gif)
 
@@ -52,6 +53,21 @@ assert!(!captree.collides(&[1.5, 1.5], 0.01));
 assert!(captree.collides(&[1.5, 1.5], 0.01));
 ```
 
+## Installation
+
+`capt` is available as a package on [crates.io](https://crates.io/crate/capt).
+This means that adding `capt` to your Rust project is as simple as asking Cargo to add it as a dependency.
+
+```sh
+cargo add capt
+```
+
+To use the SIMD-parallel features of CAPTs, make sure to include it as a feature.
+
+```sh
+cargo add capt --features simd
+```
+
 ## License
 
 This work is licensed to you under the Apache 2.0 license.