AxisOptions.autoRotation add missing boolean type (#36919)

Reference: https://api.highcharts.com/highcharts/xAxis.labels.autoRotation

types/highcharts/index.d.ts

@@ -8,6 +8,7 @@
 //                 ArunkeshavaReddy Sankaramaddi <https://github.com/Arunkeshavareddy>
 //                 Dolan Miu <https://github.com/dolanmiu>
 //                 Jack Siman <https://github.com/jjsiman>
+//                 Matthew Wills <https://github.com/mdotwills>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 2.3
 
@@ -82,7 +83,7 @@ declare namespace Highcharts {
          * @default [-45]
          * @since 4.1.0
          */
-        autoRotation?: number[];
+        autoRotation?: number[] | boolean;
         /**
          * When each category width is more than this many pixels, we don't apply auto rotation. Instead, we lay out the
          * axis label with word wrap. A lower limit makes sense when the label contains multiple short words that don't

types/highcharts/test/index.ts

@@ -2397,6 +2397,12 @@ function test_AxisOptions() {
             ['minute', [1, 2, 5, 10, 15, 30]]],
         visible: true
     };
+
+    const labelsOptionUnions: Highcharts.AxisOptions = {
+        labels: {
+            autoRotation: false
+        }
+    };
 }
 
 function test_AxisObject() {