Allow category label definition at axis level

docs/axes/cartesian/category.md

@@ -2,6 +2,38 @@
 
 The category scale will be familiar to those who have used v1.0. Labels are drawn from one of the label arrays included in the chart data. If only `data.labels` is defined, this will be used. If `data.xLabels` is defined and the axis is horizontal, this will be used. Similarly, if `data.yLabels` is defined and the axis is vertical, this property will be used. Using both `xLabels` and `yLabels` together can create a chart that uses strings for both the X and Y axes.
 
+Specifying any of the settings above implicitly defines the x axis as `type: category`if not defined otherwise. For more fine-grained control of category labels, it is (as of 2.7) also possible to add `labels` as part of the explicit category axis definition.
+
+## Category Axis Definition
+
+Implicit:
+
+```javascript
+let chart = new Chart(ctx, {
+    type: ...
+    data: {
+        labels: ['January', 'February', 'March', 'April', 'May', 'June'],
+        datasets: ...
+    },
+});
+```
+Explicit:
+
+```javascript
+let chart = new Chart(ctx, {
+    type: ...
+    data: ...
+    options: {
+        scales: {
+            xAxes: [{
+                type: 'category',
+                labels: ['January', 'February', 'March', 'April', 'May', 'June'],
+            }]
+        }
+    }
+});
+```
+
 ## Tick Configuration Options
 
 The category scale provides the following options for configuring tick marks. They are nested in the `ticks` sub object. These options extend the [common tick configuration](README.md#tick-configuration).

src/scales/scale.category.js

@@ -15,7 +15,7 @@ module.exports = function(Chart) {
 		*/
 		getLabels: function() {
 			var data = this.chart.data;
-			return (this.isHorizontal() ? data.xLabels : data.yLabels) || data.labels;
+			return this.options.labels || (this.isHorizontal() ? data.xLabels : data.yLabels) || data.labels;
 		},
 
 		determineDataLimits: function() {