text: module.exports = {
      '@vuepress/pwa': {
          serviceWorker: true,
          updatePopup: {
              message: "发现新内容可用.",
              buttonText: "刷新"
          }
      },
      '@vuepress/back-to-top': true,
      '@vuepress/medium-zoom': {
          selector: '.theme-default-content:not(.custom) img',
          // medium-zoom options here
          // See: https://github.com/francoischalifour/medium-zoom#options
          options: {
              margin: 16
          }
      }
  }
  