delete a tag. use span tag

src/client/js/components/PageEditorByHackmd.jsx

@@ -243,9 +243,9 @@ class PageEditorByHackmd extends React.Component {
       content = (
         <div>
           <p className="text-center hackmd-status-label"><i className="fa fa-file-text"></i> { t('hackmd.not_set_up')}</p>
-          <a href="https://docs.growi.org/ja/admin-guide/admin-cookbook/integrate-with-hackmd.html">
+          <span>
             {t('hackmd.need_to_associate_with_growi_to_use_hackmd_refer_to_this')}
-          </a>
+          </span>
         </div>
       );
     }