Updated readme, added defaults

Author: kyranet

README.md

@@ -13,7 +13,7 @@ const { Canvas } = require('canvas-constructor');
 
 new Canvas(300, 300)
     .setColor('#AEFD54')
-    .fillRect(5, 5, 290, 290)
+    .addRect(5, 5, 290, 290)
     .setColor('#FFAE23')
     .setTextFont('28px Impact')
     .addText('Hello World!', 130, 150)

src/canvas.js

@@ -242,7 +242,7 @@ class CanvasConstructor {
      * @returns {CanvasConstructor}
      * @chainable
      */
-    addRoundImage(buffer, x, y, width, height, radius) {
+    addRoundImage(buffer, x, y, width, height, radius = 10) {
         return this.addImage(buffer, x, y, width, height, { type: 'round', radius });
     }
 
@@ -257,7 +257,7 @@ class CanvasConstructor {
      * @returns {CanvasConstructor}
      * @chainable
      */
-    addBevelImage(buffer, x, y, width, height, radius) {
+    addBevelImage(buffer, x, y, width, height, radius = 10) {
         return this.addImage(buffer, x, y, width, height, { type: 'bevel', radius });
     }