doc: fix echo when running with sudo

doc/quick-install.md

@@ -22,7 +22,7 @@ Finally on the same machine test that you can ping the FQDN with: `ping "$(hostn
 
 ### Add the Jitsi package repository
 ```sh
-echo 'deb https://download.jitsi.org stable/' >> /etc/apt/sources.list.d/jitsi-stable.list
+echo 'deb https://download.jitsi.org stable/' | sudo tee /etc/apt/sources.list.d/jitsi-stable.list
 wget -qO -  https://download.jitsi.org/jitsi-key.gpg.key | sudo apt-key add -
 ```
 ### Open ports in your firewall