Update README.md
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<p>Use the Sketch Editor to edit, or sketch a new point, line, or polygon geometry on to a map. </p>
+<p><img src="SketchOnMap.png"/></p>
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<h2>How to use the sample</h2>
<p>Use the drop down menu to choose which geometry type to sketch. Choose from points, multipoints, polygons, freehand lines and freehand polgons.</p>
