Modify main README to add k-Means

Author: johnsgill3

README.markdown

@@ -94,17 +94,13 @@ Bad sorting algorithms (don't use these!):
 - Statistics
 
 ### Machine learning
-
-##### Supervised learning
+- [k-Means](K-Means/). Unsupervised classifier that partitions data into k clusters.
 - k-Nearest Neighbors
 - Linear Regression
 - Logistic Regression
 - Neural Networks
 - PageRank
 
-##### Clustering
-- [k-Means](K-Means/). Unsupervised classifier that partitions data into k clusters.
-
 ## Data structures
 
 The choice of data structure for a particular task depends on a few things.