Update GeoPoint.md

Author: Ehesp

v3.0.*/firestore/reference/GeoPoint.md

@@ -1,11 +1,11 @@
 # GeoPoint
 
 ```
-firebase.firestore.geoPoint
+new firebase.firestore.GeoPoint
 ```
 
-### geoPoint
-[method]geoPoint(latitude, longitude);[/method]
+### GeoPoint
+[method]new GeoPoint(latitude, longitude);[/method]
 
 An immutable object representing a geo point in Cloud Firestore. The geo point is represented as latitude/longitude pair.