Update image in demo.html

examples/browser/demo.html

@@ -127,7 +127,7 @@ function recognizeFile(file){
 <option value='vie'     > Vietnamese            </option>
 </select>
 
-<button onclick="recognizeFile('../../tests/assets/images/testocr.png')">Sample Image</button>
+<button onclick="recognizeFile('../../tests/assets/images/simple.png')">Sample Image</button>
 <input type="file" onchange="recognizeFile(window.lastFile=this.files[0])">
 
 <div id="log"></div>