docs: add release flag to cargo build (#8992)

### Description

Closes #8986

### Testing Instructions

docs/repo-docs/guides/multi-language.mdx

@@ -55,7 +55,7 @@ Then, add a `package.json` to the directory:
 {
   "name": "@repo/rust-cli",
   "scripts": {
-    "build": "cargo build"
+    "build": "cargo build --release"
   }
 }
 ```