Add site.copyright and site.copyright_url config options (#4313)

* Allow to optionally define website copyright holder name and url using site.copyright and site.copyright_url

* Update _config.yml

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Co-authored-by: iBug <git@ibugone.com>

_config.yml

@@ -29,6 +29,8 @@ logo                     : # path of logo image to display in the masthead, e.g.
 masthead_title           : # overrides the website title displayed in the masthead, use " " for no title
 # breadcrumbs            : false # true, false (default)
 words_per_minute         : 200
+copyright                : # "copyright" name, defaults to site.title
+copyright_url            : # "copyright" URL, defaults to site.url
 comments:
   provider               : # false (default), "disqus", "discourse", "facebook", "staticman", "staticman_v2", "utterances", "giscus", "custom"
   disqus:

_includes/footer.html

@@ -18,4 +18,4 @@
   </ul>
 </div>
 
-<div class="page__footer-copyright">&copy; {{ site.time | date: '%Y' }} {{ site.name | default: site.title }}. {{ site.data.ui-text[site.locale].powered_by | default: "Powered by" }} <a href="https://jekyllrb.com" rel="nofollow">Jekyll</a> &amp; <a href="https://mademistakes.com/work/minimal-mistakes-jekyll-theme/" rel="nofollow">Minimal Mistakes</a>.</div>
+<div class="page__footer-copyright">&copy; {{ site.time | date: '%Y' }} <a href="{{ site.copyright_url | default: site.url }}">{{ site.copyright | default: site.title }}</a>. {{ site.data.ui-text[site.locale].powered_by | default: "Powered by" }} <a href="https://jekyllrb.com" rel="nofollow">Jekyll</a> &amp; <a href="https://mademistakes.com/work/minimal-mistakes-jekyll-theme/" rel="nofollow">Minimal Mistakes</a>.</div>