Update docs/guide.md

Author: jsjoeio

docs/guide.md

@@ -261,7 +261,7 @@ Make sure to substitute `[email protected]` with your actual email.
 
 Visit `https://<your-domain-name>` to access `code-server`. Congratulations!
 
-Note: if you set `proxy_set_head Host $host;` in your reverse proxy config, it will change the address displayed in the green section of code-server in the bottom left to show the correct address.
+Note: if you set `proxy_set_header Host $host;` in your reverse proxy config, it will change the address displayed in the green section of code-server in the bottom left to show the correct address.
 
 ### Self Signed Certificate