docs fixes

src/Node.js

@@ -2095,10 +2095,10 @@
    * @param {Number} blur
    * @returns {Number}
    * @example
-   * // get shadow blur
+   * // get globalCompositeOperation
    * var globalCompositeOperation = shape.globalCompositeOperation();
    *
-   * // set shadow blur
+   * // set globalCompositeOperation
    * shape.globalCompositeOperation('source-in');
    */
   Konva.Factory.addGetterSetter(Konva.Node, 'opacity', 1);