added setter for newly added leg annotation

Author: Cameron Mace

mapbox/libjava-services/src/main/java/com/mapbox/services/api/directions/v5/models/RouteLeg.java

@@ -113,4 +113,8 @@ public void setSteps(List<LegStep> steps) {
   public LegAnnotation getAnnotation() {
     return annotation;
   }
+
+  public void setAnnotation(LegAnnotation annotation) {
+    this.annotation = annotation;
+  }
 }