feat: 去掉顶部pdf展览

src/pages/explain/index_pdf.vue

@@ -2,8 +2,8 @@
   <!-- npm install vue-pdf@4.3.0 -->
   <!-- npm install vue-pdf@1.0.2 -->
   <!-- pdf_container -->
-  <div class="preview_pdf">
-    <h1 style="text-align: center">PDF在线预览</h1>
+  <div>
+    <!-- <h1 style="text-align: center">PDF在线预览</h1> -->
     <!-- <div style="text-align: center">
       <button id="prev" @click="prevPage">上一页</button>
       <button id="next" @click="nextPage">下一页</button>