fix: set default locale for lang attribute

Jacky Zhao

2024-02-08 a87704cd05e379c670abce823385fb937a65920d

 docs/advanced/making plugins.md

@@ -278,7 +278,7 @@
          allFiles,
        }

        const content = renderPage(slug, componentData, opts, externalResources)
        const content = renderPage(cfg, slug, componentData, opts, externalResources)
        const fp = await emit({
          content,
          slug: file.data.slug!,