docs: Fix config for JS choropleth example

Author: camdecoster

_posts/plotly_js/maps/choropleth-maps/2015-08-10-countrygdp-choropleth-map.html

@@ -27,10 +27,10 @@
                 width: 0.5
             }
         },
-        tick0: 0,
         zmin: 0,
-        dtick: 1000,
         colorbar: {
+            dtick: 1000,
+            tick0: 0,
             tickmode: 'linear',
             tickprefix: '$',
             title: {text: 'GDP<br>Billions US$'}