Properly set rg for use in grep

.vimrc

@@ -65,7 +65,7 @@ let g:airline_right_sep=''
 if executable('rg')
   let g:unite_source_rec_async_command =
         \ ['rg', '--follow', '--hidden', '--files']
-  let g:unite_source_grep_command = 'ag'
+  let g:unite_source_grep_command = 'rg'
   let g:unite_source_grep_default_opts = '-i --vimgrep --hidden'
   let g:unite_source_grep_recursive_opt = ''
 elseif executable('ag')