Add a comment explaining why extend is being used

jquery.flot.pie.js

@@ -225,7 +225,8 @@ More detail and specific examples can be found in the included HTML file.
 				var value = data[i].data[0][1];
 				if (numCombined < 2 || value / total > options.series.pie.combine.threshold) {
 					newdata.push(
-						$.extend(data[i], {
+						$.extend(data[i], {     /* extend to allow keeping all other original data values
+						                           and using them e.g. in labelFormatter. */
 							data: [[1, value]],
 							color: data[i].color,
 							label: data[i].label,