[fix] Added billing address gstin number in the sales invoice and delivery note as well in the sales gst reports (#10872)

diff --git a/erpnext/regional/india/setup.py b/erpnext/regional/india/setup.py
index 2798cfb..fb40e32 100644
--- a/erpnext/regional/india/setup.py
+++ b/erpnext/regional/india/setup.py
@@ -113,12 +113,15 @@
 		]
 
 	sales_invoice_gst_fields = [
+			dict(fieldname='billing_address_gstin', label='Billing Address GSTIN',
+				fieldtype='Data', insert_after='customer_address',
+				options='customer_address.gstin', print_hide=1),
 			dict(fieldname='customer_gstin', label='Customer GSTIN',
 				fieldtype='Data', insert_after='shipping_address',
 				options='shipping_address_name.gstin', print_hide=1),
 			dict(fieldname='place_of_supply', label='Place of Supply',
 				fieldtype='Data', insert_after='customer_gstin', print_hide=1,
-				options='shipping_address_name.gst_state_number', read_only=1),
+				options='shipping_address_name.gst_state_number', read_only=0),
 			dict(fieldname='company_gstin', label='Company GSTIN',
 				fieldtype='Data', insert_after='company_address',
 				options='company_address.gstin', print_hide=1)