add optional <hr> element before comments

Author: Axel Bock

README.md

@@ -193,6 +193,7 @@ Comments is disabled by default. Enable comments in your `.Site.Params`.
 [params]
   [params.comments]
     enabled = true
+    insert_hr_line = false # inserts an <hr> element before comment block
     engine = "disqus" # default if unset
                       # other options: disqus, utterances, cactus_comments, remark42
 ```

layouts/partials/comments.html

@@ -1,5 +1,7 @@
 {{ $enable_comments := .Scratch.Get "enable_comments" }}
 {{ if $enable_comments -}}
+{{- if .Site.Params.Comments.insert_hr_line -}}<hr/>
+{{ end -}}
   <div class="blog-post-comments">
     {{ if (or (not (isset .Site.Params.Comments "engine")) (eq .Site.Params.Comments.Engine "disqus")) }}
       {{ partial "comments/disqus.html" . }}