fix: make 'lastUpdated' backward compatible

lib/prepare/resolvePlugin.js

@@ -14,7 +14,9 @@ module.exports = function (options) {
   const plugin = new Plugin(pluginContext)
 
   plugin
-    .use(lastUpdatedPlugin)
+    // 1. user plugin
+    .useByConfigs(siteConfig.plugins)
+    // 2. built-in plugins
     .use(enhanceAppPlugin)
     .use(registerGlobalComponentsPlugin, {
       baseDirs: [
@@ -22,12 +24,22 @@ module.exports = function (options) {
         path.resolve(themePath, 'components')
       ]
     })
-    .useByConfigs(siteConfig.plugins)
 
+  // 1. whether to use active header links
   const { activeHeaderLinks = true } = themeConfig
   if (activeHeaderLinks) {
     plugin.use(activeHeaderLinksPlugin)
   }
 
+  // 2. whether to use last updated
+  const shouldUseLastUpdated = (
+    themeConfig.lastUpdated ||
+    Object.keys(siteConfig.locales && themeConfig.locales || {})
+      .some(base => themeConfig.locales[base].lastUpdated)
+  )
+  if (shouldUseLastUpdated) {
+    plugin.use(lastUpdatedPlugin)
+  }
+
   return plugin
 }