Remove unnecessary Ubuntu-specific guides (#561)

Author: QuintenQVD0

community/config/nodes/add_node.md

@@ -45,7 +45,7 @@ Don't forget to account for OS overhead and other software requirements on machi
 ## Install the Daemon
 At this point you'll need to have the Daemon installed on your machine. Check out the [documentation](/wings/installing.html)
 for more information, or try one of the community guides for [CentOS](/community/installation-guides/wings/centos7.html),
-[Ubuntu](/community/installation-guides/wings/ubuntu1804.html), or [Debian](/community/installation-guides/wings/debian9.html).
+or [Debian](/community/installation-guides/wings/debian.html).
 
 ## Configuring the Node
 Go to the Node Configuration page

community/installation-guides/panel/ubuntu1804.md

@@ -18,8 +18,7 @@ only the versions listed below.
 
 | Operating System | Version |     Supported      | Notes                                                       |
 |------------------|---------|:------------------:|-------------------------------------------------------------|
-| **Ubuntu**       | 18.04   | :white_check_mark: | Documentation written assuming Ubuntu 18.04 as the base OS. |
-|                  | 20.04   | :white_check_mark: |                                                             |
+| **Ubuntu**       | 20.04   | :white_check_mark: | Documentation written assuming Ubuntu 20.04 as the base OS. |
 |                  | 22.04   | :white_check_mark: |                                                             |
 | **CentOS**       | 7       | :white_check_mark: |                                                             |
 |                  | 8       | :white_check_mark: | Note that CentOS 8 is EOL. Use Rocky or Alma Linux.         |