feat(comments): add utterances support

closes https://github.com/CaiJimmy/hugo-theme-stack/issues/21

exampleSite/config.toml

@@ -28,8 +28,12 @@ DefaultContentLanguage = "en"                   # Theme i18n support
             default = "Licensed under CC BY-NC-SA 4.0"
     [params.comments]
         enabled = true
-        # Only Disqus is available so far
+        provider = "disqus"         # Available: disqus, utterances    
-        provider = "disqus"
+        [params.comments.utterances]
+            repo = ""
+            issueTerm = "pathname"
+            label = ""             # Optional
+            theme="preferred-color-scheme"
     [params.widgets]
         enabled = ['archives', 'tag-cloud']
         [params.widgets.archives]

layouts/partials/comments/provider/utterances.html

@@ -0,0 +1,16 @@
+<script src="https://utteranc.es/client.js" 
+        repo="{{ .Site.Params.comments.utterances.repo }}"
+        issue-term="{{ .Site.Params.comments.utterances.issueTerm }}"
+        theme="{{ .Site.Params.comments.utterances.theme }}" 
+        {{ with .Site.Params.comments.utterances.label }}
+        label="{{ . }}"
+        {{ end }}
+        crossorigin="anonymous" 
+        async>
+</script>
+
+<style>
+    .utterances {
+        max-width: unset;
+    }
+</style>