Docs: add more examples (composite, greyscale, tint)

lib/composite.js

@@ -56,6 +56,21 @@ const blend = {
  * @since 0.22.0
  *
  * @example
+ * await sharp(background)
+ *   .composite([
+ *     { input: layer1, gravity: 'northwest' },
+ *     { input: layer2, gravity: 'southeast' },
+ *   ])
+ *   .toFile('combined.png');
+ *
+ * @example
+ * const output = await sharp('input.gif', { animated: true })
+ *   .composite([
+ *     { input: 'overlay.png', tile: true, blend: 'saturate' }
+ *   ])
+ *   .toBuffer();
+ *
+ * @example
  * sharp('input.png')
  *   .rotate(180)
  *   .resize(300)