Add instructions for using PADD with Docker

[goose-ws]

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[thomasmerz]

@goose-ws - Why so complicated? Just copy padd.sh to your /etc/pihole volume/mount on your linux host where docker is running. Then execute docker exec pihole /etc/pihole/padd.sh and voila!

You can also run it on another TTY on your linux host to monitor 24x7 by switching to TTY11 for example:

$ cat /etc/systemd/system/pihole-padd.service
# PADD - A more advanced version of the chronometer provided with Pihole.

[Unit]
Description=PADD - A more advanced version of the chronometer provided with Pihole.
#Requires=pihole.service
After=docker.service network-online.target dhcpd.service pihole.service

[Service]
Type=simple
Environment=TERM=linux
User=root
TTYPath=/dev/tty11
ExecStart=/usr/bin/sh -c "/usr/bin/docker exec --tty pihole /etc/pihole/padd.sh > /dev/tty11 < /dev/tty11"
ExecStop=/usr/bin/sh -c "/usr/bin/clear > /dev/tty11 < /dev/tty11"
Restart=always
RestartSec=1
TTYReset=yes
TTYVHangup=yes
TTYVTDisallocate=yes
KillSignal=SIGHUP

[Install]
WantedBy=multi-user.target

[thomasmerz]

@yubiuser , what about this PR? I find these instructions much to overcomplicated.

[yubiuser]

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