Update UK address form to be in line with GOV.UK Design System

exporter/core/organisation/forms.py

@@ -261,33 +261,31 @@ class Layout:
     )
 
     address_line_1 = AddressLineField(
-        label="Building and street",
+        label="Address line 1",
         error_messages={
-            "required": "Enter a real building and street name",
+            "required": "Enter address line 1, typically the building and street",
         },
     )
     address_line_2 = AddressLineField(
-        label="",
+        label="Address line 2 (optional)",
         required=False,
     )
 
     city = AddressLineField(
         label="Town or city",
         error_messages={
-            "required": "Enter a real city",
+            "required": "Enter town or city",
         },
     )
     region = AddressLineField(
-        label="County or state",
-        error_messages={
-            "required": "Enter a county or state",
-        },
+        label="County (optional)",
+        required=False,
     )
 
     postcode = forms.CharField(
         label="Postcode",
         error_messages={
-            "required": "Enter a real postcode",
+            "required": "Enter postcode",
         },
     )