add content for heap

DataStructure/17_Heap/README.md

@@ -2,6 +2,8 @@
 
 The `heapify` function is used to maintain the heap property in a binary tree. It plays a crucial role in building max-heaps and min-heaps, which are fundamental structures for algorithms like heap sort.
 
+- [Heap Sort Algorithm](https://algostructure.com/sorting/heapsort.php)
+
 ### `heapify` Function
 `heapify` ensures that a subtree with a given node as the root satisfies the heap property. If the subtree violates the heap property, the function rearranges the nodes so that the subtree becomes a valid max-heap or min-heap.
 
@@ -57,6 +59,8 @@ For a min-heap, `heapify` ensures that each node is less than or equal to its ch
 3. If the heap property is violated, swap the node with the largest (max-heap) or smallest (min-heap) of its children.
 4. Recursively apply `heapify` to the affected subtree.
 
+![heapify](./images/heapify.png)
+
 ### Visualizing the Max-Heap
 Initial tree before heapifying:
 ```