message: fix(theme): add external-link-icon plugin
diff: @@ -35,6 +35,7 @@ export const getPluginConfig = (
  "@vuepress/active-header-links",
  resolveActiveHeaderLinksOptions(plugins.activeHeaderLinks),
  ],
  + ["@vuepress/external-link-icon", plugins.externalLinkIcon !== false],
  ["@vuepress/nprogress", plugins.nprogress !== false],
  ["@vuepress/prismjs", plugins.prismjs !== false],
  ["@vuepress/theme-data", { themeData }],
  