Add batch number to customer invoice header

templates/customer.html

@@ -142,7 +142,7 @@
         <div class="header">
             <div>
                 <h1>Fakturaunderlag - Kund {{ customer.customer_number }}</h1>
-                <div>Period: {{ period }}</div>
+                <div>Batch: {{ batch_number }} | Period: {{ period }}</div>
             </div>
             <div class="meta">
                 <div>Genererad: {{ generated_date }}</div>