remove duplicate word in 'Remove duplicate code' :)

README.md

@@ -367,7 +367,7 @@ means that there's more than one place to alter something if you need to change
 some logic.
 
 Imagine if you run a restaurant and you keep track of your inventory: all your
-tomatoes, onions, garlic, spices, etc. If you have multiple lists that that
+tomatoes, onions, garlic, spices, etc. If you have multiple lists that
 you keep this on, then all have to be updated when you serve a dish with
 tomatoes in them. If you only have one list, there's only one place to update!