docs: remove @react-code-view/core from installation instructions

@react-code-view/core is a dependency and will be installed automatically

Author: simonguo

packages/react/README.md

@@ -5,9 +5,9 @@ React components for rendering code with live preview and syntax highlighting.
 ## Installation
 
 ```bash
-pnpm add @react-code-view/react @react-code-view/core
+pnpm add @react-code-view/react
 # or
-npm install @react-code-view/react @react-code-view/core
+npm install @react-code-view/react
 ```
 
 ## Quick Start