docs: fix dotenv link

Author: brandonbothell

docusaurus/docs/tutorial/intro.mdx

@@ -40,7 +40,7 @@ const youtube = new YouTube(process.env.YOUTUBE_API_KEY)
 
 :::danger[TAKE CARE]
 
-It is not recommended to place an API key directly in your code. Instead, use an [environment variable](https://github.com/motdotla/dotenv#-install).
+It is not recommended to place an API key directly in your code. Instead, use an [environment variable](https://github.com/motdotla/dotenv#usage).
 
 :::