Added Luck Structure diagram

docs/DeveloperGuide.md

@@ -150,6 +150,7 @@ settle the debt.
 
 The method then prints out the amount that is owed by `userName1` to `userName2`, and the amount that is owed
 by `userName2` to `userName1` after the settlement.
+
 ![Sequence Diagram](images/settle.png)
 
 ### Group Storage feature
@@ -207,12 +208,19 @@ To win in the slot machine, all three slots in the MIDDLE row must show the same
 The user can either key in `/reroll` or `/exit` to either roll the slot machine or leave the game.
 For every new `/reroll`, an additional Expense of 10USD would be created and allocated to a random member in the group 
 For a win, the user clears all his debts within the group.
+
+Following structural diagram shows the dependency of Luck class
+
+![Luck Structure](images/LuckStructure.png)
+
 Following sequence diagram shows user calls `startGambling()` within Luck class and a new SlotMachine class is instantiated
 For every reroll, fillSlots() is called which fills individual slots in the 3 x 3 slot machine with a randomised character
+
 ![Sequence Diagram](images/luckGambling.png)
 
 
 
+
 ## Product scope
 
 ### Target user profile