Add a better explanation on job generation

htdocs/compta/facture/fiche-rec.php

@@ -1256,8 +1256,13 @@ else
 		
     	print '<br>';
 		
+    	// Frequencry/Recurring section
 		if ($object->frequency > 0)
 		{
+    		if (empty($conf->cron->enabled))
+    		{
+    			print info_admin($langs->trans("EnableAndSetupModuleCron", $langs->transnoentitiesnoconv("Module2300Name")));	
+    		}
     		
     		print '<table class="border" width="100%">';
     		

htdocs/langs/en_US/admin.lang

@@ -429,6 +429,7 @@ NoDetails=No more details in footer
 DisplayCompanyInfo=Display company address
 DisplayCompanyManager=Display manager names
 DisplayCompanyInfoAndManagers=Display company and manager names
+EnableAndSetupModuleCron=If you want to have this recurring invoice beeing generated automatically, module *%s* must be enabled and correctly setup. Otherwise, generation of invoices must be done manually from this template with button *Create*. Note that even if you enabled automatic generation, you can still safely launch manual generation. Duplicates generation for same period are not possible. 
 
 # Modules
 Module0Name=Users & groups