Fix the setTimeout example not to return immediately

Author: shugo

ext/js/lib/js.rb

@@ -137,10 +137,10 @@ def respond_to_missing?(sym, include_private)
   #
   # The below examples show typical usage in Ruby
   #
-  #   JS.eval("return new Promise((ok) => setTimeout(ok(42), 1000))").await # => 42 (after 1 second)
-  #   JS.global.fetch("https://example.com").await                          # => [object Response]
-  #   JS.eval("return 42").await                                            # => 42
-  #   JS.eval("return new Promise((ok, err) => err(new Error())").await     # => raises JS::Error
+  #   JS.eval("return new Promise((ok) => setTimeout(() => ok(42), 1000))").await # => 42 (after 1 second)
+  #   JS.global.fetch("https://example.com").await                                # => [object Response]
+  #   JS.eval("return 42").await                                                  # => 42
+  #   JS.eval("return new Promise((ok, err) => err(new Error())").await           # => raises JS::Error
   def await
     # Promise.resolve wrap a value or flattens promise-like object and its thenable chain
     promise = JS.global[:Promise].resolve(self)