add k-Means algorithm

Author: johnsgill3

README.markdown

@@ -96,6 +96,7 @@ Bad sorting algorithms (don't use these!):
 
 ### Machine learning
 
+- [k-Means](K-Means/). Unsupervised classifier that partitions data into k clusters.
 - k-Nearest Neighbors
 - Linear Regression
 - Logistic Regression