Doc Installation: Support focal and drop Fedora 36

doc/installation.rst

@@ -37,6 +37,18 @@ Debian 12
     $ sudo apt update
     $ sudo apt install eduvpn-client
 
+Ubuntu 20.04
+======================================
+
+.. code-block:: console
+
+    $ sudo apt update
+    $ sudo apt install apt-transport-https wget
+    $ wget -O- https://app.eduvpn.org/linux/v4/deb/[email protected] | gpg --dearmor | sudo tee /usr/share/keyrings/eduvpn-v4.gpg >/dev/null
+    $ echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/eduvpn-v4.gpg] https://app.eduvpn.org/linux/v4/deb/ focal main" | sudo tee /etc/apt/sources.list.d/eduvpn-v4.list
+    $ sudo apt update
+    $ sudo apt install eduvpn-client
+
 Ubuntu 22.04
 ======================================
 
@@ -73,6 +85,18 @@ Ubuntu 23.04
     $ sudo apt update
     $ sudo apt install eduvpn-client
 
+Linux Mint 20.x
+======================================
+
+.. code-block:: console
+
+    $ sudo apt update
+    $ sudo apt install apt-transport-https wget
+    $ wget -O- https://app.eduvpn.org/linux/v4/deb/[email protected] | gpg --dearmor | sudo tee /usr/share/keyrings/eduvpn-v4.gpg >/dev/null
+    $ echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/eduvpn-v4.gpg] https://app.eduvpn.org/linux/v4/deb/ focal main" | sudo tee /etc/apt/sources.list.d/eduvpn-v4.list
+    $ sudo apt update
+    $ sudo apt install eduvpn-client
+
 Linux Mint 21.x
 ======================================
 
@@ -85,7 +109,7 @@ Linux Mint 21.x
     $ sudo apt update
     $ sudo apt install eduvpn-client
 
-Fedora (36, 37 & 38)
+Fedora (37 & 38)
 ====================
 
 .. code-block:: console