fix typos

Author: alex11818

assets/custom.css

@@ -1,5 +1,5 @@
-/* Piece of CSS to prettify the map attributions */
-/* Thank a lot to the post below for the tips! */
+/* A piece of CSS to prettify the map attributions */
+/* Thanks a lot to the post below for the tips! */
 /* https://community.plotly.com/t/plotly-6-map-attribution-box-positioning/91228 */
 
 /* Move attribution block outside the map */