fix: search can not search the table header (#1256)

Author: sy-records

Diff for: src/plugins/search/search.js

@@ -56,6 +56,7 @@ function getAllPaths(router) {
 
 function getTableData(token) {
   if (!token.text && token.type === 'table') {
+    token.cells.unshift(token.header);
     token.text = token.cells
       .map(function(rows) {
         return rows.join(' | ');