Add description of kNN

mini_proj/report/waldo.tex

@@ -100,7 +100,13 @@
 
 		\paragraph{$k$-Nearest Neighbors}
 
-		($k$-NN) \cite{knn}
+		($k$-NN) \cite{knn} is one of the simplest machine learning algorithms. It
+		classifies a new instance based on its ``distance'' to the known instances.
+		It will find the $k$ closest instances to the new instance and assign the
+		new instance the class that the majority of the $k$ closest instances has.
+		The method has to be configured in several ways:  the number of $k$, the
+		distance measure, and (depending on $k$) a tie breaking measure all have to
+		be chosen.
 
 		\paragraph{Support Vector Machine}