Move JS module rdoc into .rb file to include example section

rdoc somehow ignore the section in .c

Author: kateinoigakukun

ext/js/js-core.c

@@ -457,25 +457,6 @@ static VALUE _rb_js_proc_to_js(VALUE obj) {
   return jsvalue_s_new(rb_js_abi_host_proc_to_js_function((uint32_t)obj));
 }
 
-/*
- * Document-module: JS
- *
- * The JS module provides a way to interact with JavaScript from Ruby.
- *
- * == Example
- *
- * A simple eval and object access:
- *
- *   require 'js'
- *   JS.eval("return 1 + 2") # => 3
- *   JS.global[:document].write("Hello, world!")
- *   JS.global[:document].addEventListner("click") do |event|
- *     puts event          # => # [object MouseEvent]
- *     puts event[:detail] # => 1
- *   end
- *
- */
-
 /*
  * Document-class: JS::Object
  *

ext/js/lib/js.rb

@@ -1,5 +1,20 @@
 require "js.so"
 
+# The JS module provides a way to interact with JavaScript from Ruby.
+#
+# == Example
+#
+#   require 'js'
+#   JS.eval("return 1 + 2") # => 3
+#   JS.global[:document].write("Hello, world!")
+#   JS.global[:document].addEventListner("click") do |event|
+#     puts event          # => # [object MouseEvent]
+#     puts event[:detail] # => 1
+#   end
+#
+module JS
+end
+
 class JS::Object
   def method_missing(sym, *args, &block)
     if self[sym].typeof == "function"