[income-gst-statement] amend headers post Brexit

UK left EU, therefore VAT headers have now changed.

gnucash/report/reports/standard/income-gst-statement.scm

@@ -401,15 +401,15 @@ with *EUGOODS* in the account description."))
               (box-8 (lambda (s) (myneg (split-adder s eu-sales-accts))))
               (box-9 (lambda (s) (split-adder s eu-purch-accts))))
          (list
-          (vector "Box 1 VAT Sales"          box-1 #f #t #f #f)
-          (vector "Box 2 VAT Reverse EU"     box-2 #f #t #f #f)
-          (vector "Box 3 VAT Output"         box-3 #f #t #f #f)
-          (vector "Box 4 VAT Purchases"      box-4 #f #t #f #f)
-          (vector "Box 5 VAT Difference"     box-5 #f #t #f #f)
-          (vector "Box 6 Tot Sales"          box-6 #f #t #f #f)
-          (vector "Box 7 Tot Purchases"      box-7 #f #t #f #f)
-          (vector "Box 8 EU Goods Sales"     box-8 #f #t #f #f)
-          (vector "Box 9 EU Goods Purchases" box-9 #f #t #f #f)))))))
+          (vector "Box 1 VAT Sales"                         box-1 #f #t #f #f)
+          (vector "Box 2 VAT Goods Purchases from EU to NI" box-2 #f #t #f #f)
+          (vector "Box 3 VAT Output"                        box-3 #f #t #f #f)
+          (vector "Box 4 VAT Purchases"                     box-4 #f #t #f #f)
+          (vector "Box 5 VAT Difference"                    box-5 #f #t #f #f)
+          (vector "Box 6 Tot Sales"                         box-6 #f #t #f #f)
+          (vector "Box 7 Tot Purchases"                     box-7 #f #t #f #f)
+          (vector "Box 8 Net Goods Sales from NI to EU"     box-8 #f #t #f #f)
+          (vector "Box 9 Net Goods Purchases from EU to NI" box-9 #f #t #f #f)))))))
 
 ;; Define the report.
 (gnc:define-report