Updated Jellyfin Debian Repository (markdown)

Jellyfin-Debian-Repository.md

@@ -8,6 +8,10 @@ The Jellyfin packages in the repository are self-contained binaries, and do not
     ```
     wget -O - https://repo.jellyfin.org/debian/jellyfin_team.gpg.key | sudo apt-key add -
     ```
+    Note: If you still use the old key signed by Joshua from the initial releases, you can remove it after installing the new one:
+    ```
+    sudo apt-key remove 99FD1406
+    ```
 0. Add an entry to `/etc/apt/sources.list.d/jellyfin.list`:
     ```
     echo "deb https://repo.jellyfin.org/debian $( grep -Ewo -m1 --color=none 'jessie|stretch|buster' /etc/os-release || echo ubuntu ) main" | sudo tee /etc/apt/sources.list.d/jellyfin.list