add example about apt lis --upgradable in linux admin chapter

source/Installation/linux_admin.rst

@@ -441,16 +441,34 @@ You need to update the list of package, then perform the upgrade of the packages
 
 .. code-block::
 
-    sudo apt update
-    sudo apt upgrade
+    $ sudo apt update
+    $ apt list --upgradable
+    Listing... Done
+    apt/focal-updates 2.0.9 amd64 [upgradable from: 2.0.2ubuntu0.1]
+    base-files/focal-updates 11ubuntu5.6 amd64 [upgradable from: 11ubuntu5.2]
+    bash/focal-updates,focal-security 5.0-6ubuntu1.2 amd64 [upgradable from: 5.0-6ubuntu1.1]
+    bsdutils/focal-updates,focal-security 1:2.34-0.1ubuntu9.3 amd64 [upgradable from: 1:2.34-0.1ubuntu9.1]
+    dpkg/focal-updates,focal-security 1.19.7ubuntu3.2 amd64 [upgradable from: 1.19.7ubuntu3]
+    e2fsprogs/focal-updates,focal-security 1.45.5-2ubuntu1.1 amd64 [upgradable from: 1.45.5-2ubuntu1]
+    fdisk/focal-updates,focal-security 2.34-0.1ubuntu9.3 amd64 [upgradable from: 2.34-0.1ubuntu9.1]
+    gcc-10-base/focal-updates,focal-security 10.3.0-1ubuntu1~20.04 amd64 [upgradable from: 10.2.0-5ubuntu1~20.04]
+    gpgv/focal-updates,focal-security 2.2.19-3ubuntu2.2 amd64 [upgradable from: 2.2.19-3ubuntu2]
+    gzip/focal-updates,focal-security 1.10-0ubuntu4.1 amd64 [upgradable from: 1.10-0ubuntu4]
+    libapt-pkg6.0/focal-updates 2.0.9 amd64 [upgradable from: 2.0.2ubuntu0.1]
+    libblkid1/focal-updates,focal-security 2.34-0.1ubuntu9.3 amd64 [upgradable from: 2.34-0.1ubuntu9.1]
+    libc-bin/focal-updates 2.31-0ubuntu9.9 amd64 [upgradable from: 2.31-0ubuntu9.1]
+    libc6/focal-updates 2.31-0ubuntu9.9 amd64 [upgradable from: 2.31-0ubuntu9.1]
+    libcom-err2/focal-updates,focal-security 1.45.5-2ubuntu1.1 amd64 [upgradable from: 1.45.5-2ubuntu1]
+    libext2fs2/focal-updates,focal-security 1.45.5-2ubuntu1.1 amd64 [upgradable from: 1.45.5-2ubuntu1]
+    libfdisk1/focal-updates,focal-security 2.34-0.1ubuntu9.3 amd64 [upgradable from: 2.34-0.1ubuntu9.1]
+    libgcc-s1/focal-updates,focal-security 10.3.0-1ubuntu1~20.04 amd64 [upgradable from: 10.2.0-5ubuntu1~20.04]
+    ...
+
+    $ sudo apt upgrade
 
-.. code-block::
-
-    sudo apt-get update
-    sudo apt-get upgrade
 
 Debian/Ubuntu is a distros based on release, sometimes you need to switch to a new release.
-For that you need to perform a `distupgrade` but only when a new release is available.
+For that you need to perform a `dist-upgrade` but only when a new release is available.
 You will warn of new release by the package manager after a "classical" update operation.
 
 .. code-block::