Register code to the Debian alternatives system

Fixes #3541

resources/linux/debian/postinst.template

@@ -3,6 +3,12 @@
 # Copyright (c) Microsoft Corporation. All rights reserved.
 # Licensed under the MIT License. See License.txt in the project root for license information.
 
+# Register code in the alternatives system
+# Priority of 0 should never make code the default editor in auto mode as most
+# developers would prefer a terminal editor as the default.
+update-alternatives --install /usr/bin/editor editor /usr/bin/@@NAME@@ 0
+
+# Register repository as an apt source
 get_apt_config_value() {
 	echo $(apt-config dump | grep "$1 " | sed -e "s/$1 \"//" -e "s/\";$//")
 }