Fix installation detection

setup/start/cloudron-motd

@@ -4,7 +4,7 @@
 
 printf "**********************************************************************\n\n"
 
-if [[ -z "$(ls -A /home/yellowtent/boxdata/mail/dkim)" ]]; then
+if [[ -z "$(ls -A /home/yellowtent/platformdata/addons/mail/dkim)" ]]; then
     if [[ -f /tmp/.cloudron-motd-cache ]]; then
         ip=$(cat /tmp/.cloudron-motd-cache)
     elif ! ip=$(curl --fail --connect-timeout 2 --max-time 2 -q https://api.cloudron.io/api/v1/helper/public_ip | sed -n -e 's/.*"ip": "\(.*\)"/\1/p'); then