doc(statusbar.js): document setBackgroundColor()

cordova-js-src/plugin/android/statusbar.js

@@ -52,6 +52,14 @@ Object.defineProperty(statusBar, 'visible', {
     }
 });
 
+/**
+ * Sets the background color of the status bar, which will visually only have an impact,
+ * if the status bar is visible. The supported format is any valid CSS color value,
+ * like `rebeccapurple`, `#RRGGBBAA`, `rgb(255 0 153)`.
+ * If cordova-plugin-statusbar is installed, the call will be forwarded to
+ * `window.StatusBar.backgroundColorByHexString`, where alpha is only supported if
+ * `StatusBar.overlaysWebView` is set to `true`.
+ */
 Object.defineProperty(statusBar, 'setBackgroundColor', {
     configurable: false,
     enumerable: false,