Add Missing Arrow to push ProgCounter to AB

src/Main.elm

@@ -385,6 +385,11 @@ viewCu model =
                 [ Html.a [ onClick (MsgManualStep ActInstructionReg2AddressBus)] [ text "InstR -> AddrB" ]]
             , div [] []
             ]
+        , div [ class "arrow", class "up", class "top", class "arrow2"] 
+            [ div [ class "button" ] 
+                [ Html.a [ onClick (MsgManualStep ActProgrammCounter2AddressBus)] [ text "ProgCounter -> AddrB" ]]
+            , div [] []
+            ]
         , h1 [ class "header" ] [ text "Control Unit" ]
         , p []
             [ text