Permit exit page heading and markdown for condition endpoint

Author: SamJamCul

app/controllers/api/v1/conditions_controller.rb

@@ -57,6 +57,8 @@ def condition_params
       :goto_page_id,
       :skip_to_end,
       :answer_value,
+      :exit_page_heading,
+      :exit_page_markdown,
     )
   end
 

spec/requests/api/v1/conditions_controller_spec.rb

@@ -40,6 +40,8 @@
         goto_page_id: goto_page.id,
         skip_to_end: false,
         answer_value: "hello",
+        exit_page_heading: nil,
+        exit_page_markdown: nil,
       }
     end