Adding overlaying components details (#2425)

How to overlay other React components on top of the `MapView`. This was not clear from the documentation and took some research to find a solution.

README.md

@@ -221,6 +221,23 @@ For Android: LocalTile is still just overlay over original map tiles. It means t
 
 See [OSM Wiki](https://wiki.openstreetmap.org/wiki/Category:Tile_downloading) for how to download tiles for offline usage.
 
+### Overlaying other components on the map
+
+Place components you that wish to overlay `MapView` underneath the `MapView` closing tag. Absolutely position these elements.
+
+```jsx
+render() {
+  return (
+    <MapView
+      region={this.state.region}
+    />
+    <OverlayComponent
+      style={{position: “absolute”, bottom: 50}}
+    />
+  );
+}
+```
+
 ### Customizing the map style
 
 Create the json object, or download a generated one from the [google style generator](https://mapstyle.withgoogle.com/).