Custom circle render example

examples/custom-circle-render.html

@@ -0,0 +1,9 @@
+---
+layout: example.html
+title: Custom Circle Render
+shortdesc: Example of a custom circle render.
+docs: >
+  This example demonstrates the use of 'ol/style/Style' render option function to render circle feature.
+tags: "circle, feature, vector, render, custom"
+---
+<div id="map" class="map"></div>