Updated stack to allow for null references to get added

C#/Datastructures/Stack/Stack.cs

@@ -11,7 +11,7 @@ namespace C_.Datastructures.Stack
             return new Stack<T>();
         }
 
-        public static Stack<T> Create(T value)
+        public static Stack<T> Create(T? value)
         {
             //Create a new Stack with a head
             return new Stack<T>
@@ -21,7 +21,7 @@ namespace C_.Datastructures.Stack
             };
         }
 
-        public void Push(T value)
+        public void Push(T? value)
         {
             //Add an Item to the top of the stack
             Count++;