Docs/types: add Promise<T> and Array<T> #472

Changelog updates and version bump of devDeps

lib/input.js

@@ -154,7 +154,7 @@ const clone = function clone () {
  *   });
  *
  * @param {Function} [callback] - called with the arguments `(err, metadata)`
- * @returns {Promise|Sharp}
+ * @returns {Promise<Object>|Sharp}
  */
 const metadata = function metadata (callback) {
   const that = this;