fix demo axes labels

examples/demo.html

@@ -45,11 +45,13 @@
           axis: {
             x: {
               format: 'numeric',
-              range: [-100, 300]
+              range: [-100, 300],
+              label: 'x'
             },
             y: {
               invert: true,
-              range: [-100, 250]
+              range: [-100, 250],
+              label: 'y'
             },
             y1: {
               isActive: true,
@@ -70,10 +72,6 @@
             orientation: 'both',
             color: 'gray'
           },
-          labelFormat: {
-            yAxis: 'y',
-            xAxis: 'x'
-          },
           eventsCallbacks: {
             zoomOut: () => { pod.render() }
           },