New Azure maps article listing available map styles

Author: Muhammad Sehgal (Aquent LLC)

articles/azure-maps/supported-map-styles.md

@@ -42,7 +42,7 @@ This map style is a hybrid of roads and labels overlaid on top of satellite and
 * [JS Map control](https://codepen.io/azuremaps/pen/qyjbOM)
 
 ## Grayscale_Dark
-**Grayscale dark** is a dark version of the road map.
+**Grayscale dark** is a dark version of the road map style.
 
 ![gray_scale](./media/supported-map-styles/grayscale_dark.png)