update rs/README.md

rs/README.md

@@ -2,10 +2,51 @@
 
 This folder contains the Rust implementation of the Chain Selectors module.
 
-## Pre-requisites
+## Installation
+
+```shell
+cargo add --git https://github.com/smartcontractkit/chain-selectors --tag <TAG>
+```
+
+## Usage
+
+```rust
+use std::str::FromStr;
+use chainselectors::generated_chains;
+
+fn main() {
+    match generated_chains::ChainName::try_from(420) {
+        Ok(c) => {
+            assert_eq!(c, generated_chains::ChainName::EthereumTestnetGoerliOptimism1);
+        }
+        Err(_) => {
+            panic!("Failed to convert chain id to chain name");
+        }
+    }
+
+    let selector = generated_chains::chain_selector(generated_chains::ChainName::EthereumTestnetGoerliOptimism1);
+    assert_eq!(
+        selector,
+        2664363617261496610,
+    );
+
+    match generated_chains::ChainName::from_str("ethereum-testnet-goerli-optimism-1") {
+        Ok(chain) => {
+            assert_eq!(chain, generated_chains::ChainName::EthereumTestnetGoerliOptimism1);
+        }
+        Err(_) => {
+            panic!("Failed to parse chain name");
+        }
+    }
+}
+```
+
+## Dev Guide
+
+### Pre-requisites
 
 As part of the code generation, `rustfmt` is used to format the generated code. If you don't have rust toolchain installed, it will run in docker.
 
-## Build
+### Build
 
-To build the Chain Selectors module, run the `go generate ./rs` from the root of the project.
+To build the Chain Selectors module, run the `go generate ./rs` from the root of the project, or `go generate ./...` to generate all modules (not just rust).