remove plot url from geojson layers js maps example so chart is inlined

Author: Joseph Damiba

_posts/plotly_js/maps/fill-area-on-mapbox/2019-09-02-geojson_layers.html

@@ -1,6 +1,5 @@
 ---
 name: GeoJSON Layers
-plot_url: https://codepen.io/plotly/embed/zYOZVWW/?height=510&theme-id=15263&default-tab=result
 language: plotly_js
 suite: filled-area-on-mapbox
 order: 3