Update readme

Author: ivanmmarkovic

README.md

@@ -69,6 +69,10 @@ but it also contains other data structures, algorithms and problems.
 - [Binary search recursive pointers](https://github.com/ivanmmarkovic/Problem-Solving-with-Algorithms-and-Data-Structures-using-Python/blob/master/searching/binary-search-recursive-pointers.py)
 
 ### [Sorting](https://github.com/ivanmmarkovic/Problem-Solving-with-Algorithms-and-Data-Structures-using-Python/tree/master/sorting)
+- [Bubble sort](https://github.com/ivanmmarkovic/Problem-Solving-with-Algorithms-and-Data-Structures-using-Python/blob/master/sorting/bubble-sort.py)
+- [Short bubble](https://github.com/ivanmmarkovic/Problem-Solving-with-Algorithms-and-Data-Structures-using-Python/blob/master/sorting/short-bubble.py)
+- [Insertion sort](https://github.com/ivanmmarkovic/Problem-Solving-with-Algorithms-and-Data-Structures-using-Python/blob/master/sorting/insertion-sort.py)
+- [Selection sort](https://github.com/ivanmmarkovic/Problem-Solving-with-Algorithms-and-Data-Structures-using-Python/blob/master/sorting/selection-sort.py)
 
 ### [Graphs](https://github.com/ivanmmarkovic/Problem-Solving-with-Algorithms-and-Data-Structures-using-Python/tree/master/graphs)
 - [Dijkstra algorithm - Shortest path](https://github.com/ivanmmarkovic/Problem-Solving-with-Algorithms-and-Data-Structures-using-Python/tree/master/graphs/dijkstra)