feat: support defining Mastodon toot URL

layouts/partials/comments.html

@@ -30,3 +30,4 @@
 <script>var MastodonUser="{{ .Site.Params.mastodoncomments.user }}"</script>
 <script>var BlogRegex="{{ .Site.Params.mastodoncomments.regex }}"</script>
 <script>var CommentsContact="{{ .Site.Params.mastodoncomments.contact }}"</script>
+<script>var MastodonTootUrl="{{ .Params.mastodon_toot_url }}"</script>