Add modify time

Gemfile

@@ -22,6 +22,7 @@ group :jekyll_plugins do
   gem 'jekyll-sitemap', '~> 1.4'
   gem 'jekyll-compose', '~> 0.12.0'
   gem 'jekyll-postfiles', '~> 3.1'
+  gem "jekyll-last-modified-at"
 end
 
 # Windows does not include zoneinfo files, so bundle the tzinfo-data gem

_config.yml

@@ -66,3 +66,7 @@ plugins:
   - jekyll-feed
   - jekyll-sitemap
   - jekyll-postfiles
+  - jekyll-last-modified-at
+
+last-modified-at:
+    date-format: 'Last updated at %B %d, %Y at %I:%M %p UTC%:::z'

_includes/footer.html

@@ -1,5 +1,7 @@
 <footer class="footer">
   <span>&copy; {{ site.time | date: "%Y" }} Swee, Savalio, and other SweeBlogs contributors.</span>
   <br>
+  <small>{% last_modified_at %}</small>
+  <br>
   <small>Made with Jekyll</small>
 </footer>