Adapted minecraft-demo to new mapping names.

https://github.com/jeromeetienne/AR.js/pull/528#issuecomment-493348055

aframe/demos/demo-minecraft-launch-demo/minecraft.html

@@ -16,7 +16,7 @@
 </div>
         <a-scene embedded arjs='sourceType: image; sourceUrl:../../../data/images/armchair.jpg; detectionMode: mono_and_matrix;' antialias="true">        
 
-		<a-marker type='unknown' minConfidence='0'>                
+		<a-marker type='unknown' min-confidence='0'>
 		<!-- <a-marker type='pattern' url='../../data/data/patt.hiro' size='1'> -->
 	                <!-- Add a minecraft character -->
 	                <a-minecraft></a-minecraft>