Add digital ProductType

Author: lwalker-ch

src/main/java/uk/gov/companieshouse/orders/api/model/ProductType.java

@@ -23,8 +23,10 @@ public enum ProductType {
     MISSING_IMAGE_DELIVERY_MISC,
     CERTIFIED_COPY,
     CERTIFIED_COPY_SAME_DAY,
+    CERTIFIED_COPY_DIGITAL,
     CERTIFIED_COPY_INCORPORATION,
-    CERTIFIED_COPY_INCORPORATION_SAME_DAY;
+    CERTIFIED_COPY_INCORPORATION_SAME_DAY,
+    CERTIFIED_COPY_INCORPORATION_DIGITAL;
 
     @JsonValue
     public String getJsonName() {