Create new bash script under /etc/update-motd.d/. For example 99-footer file which will be executed after all other files in that directory:

#! /bin/bash
 
# Ansi color codes
blue="\e[0;94m"
reset="\e[0m"
 
echo "=== Aliases set up: ==="
# -e enables interpretation of escape sequences so that the colors work
echo -e "${blue}dockip <containerid> - get ip of container${reset}"

Try figlet command for pretty output.

• Debian 10.8

• https://techstop.github.io/bash-script-colors/
• https://linux.die.net/man/6/figlet