fix: ensure the services directory also exists

Without this, we get issues attempting to install datastore plugins.

Closes #5614

docker/etc/my_init.d/10_dokku_init

@@ -36,13 +36,15 @@ main() {
     mkdir -p /mnt/dokku
   fi
 
-  directories=("/etc/ssh" "/home/dokku" "/var/lib/dokku/config" "/var/lib/dokku/data")
+  directories=("/etc/ssh" "/home/dokku" "/var/lib/dokku/config" "/var/lib/dokku/data" "/var/lib/dokku/services")
   for dir in "${directories[@]}"; do
     if [[ ! -e "$dir" ]]; then
       log-info "Copying ${dir} skel into place"
       mkdir -p "/mnt/dokku${dir}"
+      if [[ -d "$dir" ]]; then
         rsync -a "/skel${dir}/" "${dir}/" || log-fail "Unable to copy ${dir} skel into place"
       fi
+    fi
 
     # chown mount directories to "dokku:dokku"
     if [[ "$dir" != "/etc/ssh" ]]; then