Update README.md

Author: RCCoop

README.md

@@ -34,6 +34,7 @@ public struct GPXDocument {
     public var creator: String?
     public var waypoints: [GPXWaypoint]
     public var tracks: [GPXTrack]
+    public var routes: [GPXRoute]
 }
 ```
 
@@ -42,6 +43,8 @@ public struct GPXDocument {
 - GPXTrack
     - .Segment
     - .Point
+- GPXRoute
+    - .Point
 - GPXWaypoint
 
 # Reading GPX Files