Improve install instructions

Author: timolins

README.md

@@ -6,8 +6,11 @@ Renders your Notion blocks with ease.
 
 ```bash
 npm install react-notion
+```
+
+If you use code blocks and want syntax highlighting, install `primsjs`.
 
-// if you use code blocks with syntax highlighting
+```bash
 npm install prismjs
 ```