delete html

_includes/utterances.html

@@ -1,9 +1 @@
-<!-- from https://github.com/utterance/utterances -->
-<!-- <script src="https://utteranc.es/client.js"
-        repo="{{ site.github_username }}/{{ site.github_repo | default: site.baseurl | remove: "/" }}"
-        issue-term="title"
-        label="blogpost-comment"
-        theme="github-light"
-        crossorigin="anonymous"
-        async>
-</script> -->
+<!-- from https://github.com/utterance/utterances -->