Update command to start development server

Author: EstherIkechukwu

README.md

@@ -193,7 +193,7 @@ SwiftChain-Frontend/
 
 4.  **Run the development server:**
     ```bash
-    npm run dev
+    pnpm dev
     ```
 
     Open [http://localhost:3000](http://localhost:3000) with your browser to see the result.