Added Reson to cant open

Addons/Guis/rockets.lua

@@ -64,7 +64,10 @@ Gui.left.add{
             }
         end
     end,
-    can_open=function(player) return player.force.get_item_launched('satellite') > 0 end
+    can_open=function(player) 
+        if player.force.get_item_launched('satellite') > 0 then return true
+        else return {'rockets.none'} end
+    end
 }
 
 Event.register(defines.events.on_rocket_launched,function(event) Gui.left.update('rockets') end)

locale/en/rockets.cfg

@@ -1,6 +1,7 @@
 [rockets]
 name=Rocket Info
 tooltip=List of details about the rockets sent.
+none=No rockets have been sent yet.
 nan=NaN
 sent=Rockets Sent: __1__
 first=First Lanuched At: __1__