hugo-bootswatch-slate/layouts/partials/copyright.html

<div class="col-12 col-md-4">
  <div class="small-print">
    <small>{{ .Site.Copyright | safeHTML }}</small>
  </div>
  <div class="small-print">
    <small>Built with&nbsp;<a href="https://gohugo.io/" target="_blank">Hugo</a></small>
    <small>Theme&nbsp;<a href="https://github.com/gardient/hugo-bootswatch-slate" target="_blank">Hugo Bootswatch Slate</a></small>
  </div>
</div>