📝 Add command in "How to install Nginx on Ubuntu 20.04" (#1170)

Author: svenja11

tutorials/how-to-install-nginx-on-ubuntu-20-04/01.en.md

@@ -258,6 +258,7 @@ Now, that all necessary changes were made we can test our `Nginx` configuration.
 For this execute the following command:
 
 ```shell
+holu@10.0.0.1:~$ sudo rm /etc/nginx/sites-enabled/default && sudo rm /etc/nginx/sites-available/default
 holu@10.0.0.1:~$ sudo nginx -t
 ```