Update ubuntu.md

I changed 
sudo apt-get install ./docker-desktop-amd64.deb
to 
sudo dpkg -i ./docker-desktop-amd64.deb

Because I got this  error with command apt-get install 
N: Download is performed unsandboxed as root as file './docker-desktop-amd64.deb' couldn't be accessed by user '_apt'. - pkgAcquire::Run (13: Permission denied)

Author: Knase

content/manuals/desktop/setup/install/linux/ubuntu.md

@@ -47,7 +47,7 @@ Recommended approach to install Docker Desktop on Ubuntu:
 
    ```console
    $ sudo apt-get update
-   $ sudo apt-get install ./docker-desktop-amd64.deb
+   $ sudo dpkg -i ./docker-desktop-amd64.deb
    ```
 
    > [!NOTE]