Update README.markdown

Added Z-algorithm link.

Author: kelvinlauKL

README.markdown

@@ -50,6 +50,7 @@ If you're new to algorithms and data structures, here are a few good ones to sta
 - [k-th Largest Element](Kth Largest Element/). Find the *k*-th largest element in an array, such as the median.
 - [Selection Sampling](Selection Sampling/). Randomly choose a bunch of items from a collection.
 - [Union-Find](Union-Find/). Keeps track of disjoint sets and lets you quickly merge them.
+- [Z-Algorithm](Z-Algorithm/). Finds all instances of a pattern in a String, and returns the indexes of where the pattern starts within the String.
 
 ### String Search