Added documentation

Author: Satre95

Ternary Search Tree/TSTNode.swift

@@ -8,22 +8,42 @@
 
 import Foundation
 
+/**
+ This class represents a node in the Ternary Search Tree. 
+ A node has two main data members, the key and the data. 
+ All nodes in a TST must have keys, but only some will have data.
+ This can be seen in the way the data variable is of Optional type.
+*/
 class TSTNode<Element> {
     //Member properties of a particular node.
+    
+    /// The key that identifies this node.
     var key: Character
+    /// The data stored in this node. May be `nil`
     var data: Element?
+    /// Boolean flag to depict whether this node holds data or not.
     var hasData: Bool
 
-    //Children
+    /// The children of this node
     var left: TSTNode?, right: TSTNode?, middle: TSTNode?
 
-    
+    /**
+     Initializer for key and/or data
+     
+     - parameter key:  The key to set for this node.
+     - parameter data: The optional data to set in this node.
+     */
     init(key: Character, data: Element?) {
         self.key = key
         self.data = data
         self.hasData = (data != nil)
     }
 
+    /**
+     Make a node that only has a key
+    
+     - parameter key: The key to ascribe to this node.
+     */
     init(key:Character) {
         self.key = key
         self.data = nil