Include instructions if hostid2 is empty

include/data_upload

@@ -243,6 +243,13 @@
         else
             echo "${RED}Error${NORMAL}: No hostid and/or hostid2 found. Can not upload report file."
             echo "Suggested command: lynis show hostids"
+            echo ""
+            echo "If hostid2 is the only ID that is missing, use the following step:"
+            echo "Create hash and add it to custom.prf"
+            echo "echo \"hostid2=\$(cat /dev/urandom | tr -dc 'a-f0-9' | fold -w 64 | head -n 1)\" > /etc/lynis/custom.prf" 
+            echo ""
+            echo "Note: do not replicate this ID to other systems, as it needs to be unique per system"
+
             # Quit
             ExitFatal
         fi