Revert "Restore the year of first publication in footer"

This reverts commit 338eddb454.

_data/rights.yml

@@ -1,8 +1,5 @@
 #  License data
 
-# The year you first published your website, format: YYYY
-first_publication_year:   # e.g., 2021
-
 license:
   name: CC BY 4.0
   link: "https://creativecommons.org/licenses/by/4.0/"

_includes/footer.html

@@ -6,26 +6,13 @@
   <div class="d-flex justify-content-between align-items-center">
     <div class="footer-left">
       <p class="mb-0">
-        ©
-        <!-- years range -->
-        {% assign this_year = "now" | date: "%Y" | plus: 0 %}
-        {% assign years_range = this_year %}
-        {% if site.data.rights.first_publication_year < this_year
-          and site.data.rights.first_publication_year %}
-          {{ site.data.rights.first_publication_year }} -
-        {% endif %}
-        {{ this_year }}
-        <!-- copyright owner -->
+        © {{ 'now' | date: "%Y" }}
         <a href="{{ site.social.links[0] }}">{{ site.social.name }}</a>.
-        <!-- copyright statement -->
         {% if site.data.rights.brief %}
         <span data-toggle="tooltip" data-placement="top"
-          title="{{ site.data.rights.verbose }}">
-          {{ site.data.rights.brief }}
-        </span>
+          title="{{ site.data.rights.verbose }}">{{ site.data.rights.brief }}</span>
         {% endif %}
       </p>
-
     </div>
 
     <div class="footer-right">