增加输入提示

editor.html

@@ -74,8 +74,8 @@
       <h3 class="leftTabHeader">图块属性&nbsp;&nbsp;<button onclick="editor.mode.onmode('save')">save</button></h3>
       <div class="leftTabContent">
       <div id='newIdIdnum'><!-- id and idnum -->
-        <input placeholder="输入新id"/>
-        <input placeholder="输入新idnum"/>
+        <input placeholder="输入新id（唯一标识符）"/>
+        <input placeholder="输入新idnum（数字，1000以内）"/>
         <button>save</button>
       </div>
       <div><!-- enemy and item -->