Purchaser code hint text (#879)

app/models/form/sales/questions/purchaser_code.rb

@@ -4,6 +4,7 @@ class Form::Sales::Questions::PurchaserCode < ::Form::Question
     @id = "purchid"
     @check_answer_label = "Purchaser code"
     @header = "What is the purchaser code?"
+    @hint_text = "This is how you usually refer to the purchaser on your own systems."
     @type = "text"
     @width = 10
     @page = page

spec/models/form/sales/questions/purchaser_code_spec.rb

@@ -19,6 +19,10 @@ RSpec.describe Form::Sales::Questions::PurchaserCode, type: :model do
     expect(question.header).to eq("What is the purchaser code?")
   end
 
+  it "has the correct hint_text" do
+    expect(question.hint_text).to eq("This is how you usually refer to the purchaser on your own systems.")
+  end
+
   it "has the correct check_answer_label" do
     expect(question.check_answer_label).to eq("Purchaser code")
   end