docs(search): 调整搜索框占位符内容

Author: Light

src/search.php

@@ -2,7 +2,7 @@
   <div class="search">
     <div class="search-box">
       <span class="search-icon" style="background: url(<?php echo THEME_URL ?>/images/search_icon.png) 0px 0px; opacity: 1;"></span>
-      <input type="text" id="txt" class="search-input"  autocomplete="off"  placeholder="请输入关键字，按回车 / Enter 搜索">
+      <input type="text" id="txt" class="search-input"  autocomplete="off"  placeholder="输入关键字，按下回车搜索">
       <button class="search-btn" id="search-btn"><i class="fa fa-search"></i></button>
     </div>
     <!-- 搜索索引 -->