navigation: add more verbose docs

Add more parameter documentation to position event
in README.md

Bug-AGL: SPEC-2880
Change-Id: Iaabc355752a24fd931b86befdb80738faf7c2dca
Signed-off-by: Matt Ranostay <matt.ranostay@konsulko.com>

README.md

@@ -38,8 +38,11 @@ Populate same data referenced in *waypoints Event* section for the event
 {
   "points": [
     {
+      "position": "car",
       "latitude": 36.12906,
       "longitude": -115.17908
+      "direction": 273.0,
+      "distance": 1530.45
     }
   ]
 }