Improve delete-account script and documentation

Delete User Cccount

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1. Delete email account and data

    - login to mail.$DOMAIN

    - click on domain list

    - select the correct domain

    - search for the username on the top right

    - delete the correct account

2. delete nextcloud account

1. Delete email account, Nextcloud account and all data

    - `ssh user@$DOMAIN`

    - `cd /mnt/repo-base/`

    - `sudo docker-compose exec -u www-data nextcloud php occ user:delete user@$DOMAIN`

    - `sudo ./scripts/delete-account $USER`

4. onlyoffice data

2. onlyoffice data

    - go to [https://office.$DOMAIN/products/people/#sortorder=ascending](https://office.$DOMAIN/products/people/#sortorder=ascending)

    - search for the username

    - click on the arrow at the far right and press "Delete profile"

ACCOUNT=$1

if ! docker-compose exec -T -u www-data nextcloud php occ user:info "$ACCOUNT" | grep "$ACCOUNT" --quiet; then

    echo "Error: The account $ACCOUNT does not exist"

    exit

fi

echo "Please confirm to delete the user account $ACCOUNT including all data. This is not reversible."

read -r -p "[y/N] " response

if [[ $response =~ ^([yY][eE][sS]|[yY])$ ]]; then

    echo "Deleting Nextcloud account"

    docker-compose exec -T -u www-data nextcloud php occ user:delete "$ACCOUNT"

    echo "Deleting email account"

    docker-compose exec -T postfixadmin /postfixadmin/scripts/postfixadmin-cli mailbox delete "$ACCOUNT"

    # TODO: delete onlyoffice account???

fi