Update state-management.md (#2422)

The previous code example was misleading and it should be viewState instead of newCenter

Co-authored-by: Chris Gervang <chrisgervang@users.noreply.github.com>

docs/get-started/state-management.md

@@ -80,7 +80,7 @@ function App() {
     const newCenter = [viewState.longitude, viewState.latitude];
     // Only update the view state if the center is inside the geofence
     if (turf.booleanPointInPolygon(newCenter, GEOFENCE)) {
-      setViewState(newCenter);
+      setViewState(viewState);
     }
   }, [])