手动添加备案信息

修改主题目录下的文件 themes\PaperMod\layouts\partials\footer.html

<footer class="footer">
    {{- if .Site.Copyright }}
    <span>{{ .Site.Copyright | markdownify }}</span>
    {{- else }}
    <span>&copy; {{ now.Year }} <a href="{{ "" | absLangURL }}">{{ .Site.Title }}</a></span>
    {{- end }}
    <span>
        Powered by
        <a href="https://gohugo.io/" rel="noopener noreferrer" target="_blank">Hugo</a> &
        <a href="https://git.io/hugopapermod" rel="noopener" target="_blank">PaperMod</a> &
        <a href="https://beian.miit.gov.cn/" rel="noopener" target="_blank">备案号</a>
    </span>
</footer>

注意 工信部首页地址，为HTTPS，且无www