Fix JSON validity in README

Refs #45

README.md

@@ -96,7 +96,7 @@ You can customize the tile layer used  by the maps using the `tile_layer` and `t
             "tile_layer": "https://{s}.tile.opentopomap.org/{z}/{x}/{y}.png",
             "tile_layer_options": {
                 "attribution": "Map data: &copy; <a href='https://www.openstreetmap.org/copyright'>OpenStreetMap</a> contributors, <a href='http://viewfinderpanoramas.org'>SRTM</a> | Map style: &copy; <a href='https://opentopomap.org'>OpenTopoMap</a> (<a href='https://creativecommons.org/licenses/by-sa/3.0/'>CC-BY-SA</a>)",
-                "maxZoom": 17,
+                "maxZoom": 17
             }
         }
     }