Add jekyll-feed gem to enable atom feed (#372)

* Add jekyll-feed gem to Gemfile and dependencies

This commit adds the 'jekyll-feed' gem to the Gemfile and its corresponding dependency in the Gemfile.lock and _config.yml files.

The atom feed is then available at /feed.xml

* Add autodiscovery metatag for atom feed to header.html

* Use the built-in feed_meta tag

* Add rss icon to the footer

Gemfile

@@ -5,6 +5,7 @@ gem 'jekyll', '~> 4.2.2'
 gem 'jekyll-redirect-from', '~> 0.16.0'
 gem 'jekyll-seo-tag', '~> 2.8.0'
 gem 'jekyll-sitemap', '~> 1.4.0'
+gem 'jekyll-feed', '~> 0.17.0'
 gem 'wdm', '~> 0.1.1', :install_if => Gem.win_platform?
 
 gem "webrick", "~> 1.7"

Gemfile.lock

@@ -41,6 +41,8 @@ GEM
       rouge (~> 3.0)
       safe_yaml (~> 1.0)
       terminal-table (~> 2.0)
+    jekyll-feed (0.17.0)
+      jekyll (>= 3.7, < 5.0)
     jekyll-redirect-from (0.16.0)
       jekyll (>= 3.3, < 5.0)
     jekyll-sass-converter (2.2.0)
@@ -98,6 +100,7 @@ PLATFORMS
 DEPENDENCIES
   html-proofer (~> 3.19.3)
   jekyll (~> 4.2.2)
+  jekyll-feed (~> 0.17.0)
   jekyll-redirect-from (~> 0.16.0)
   jekyll-seo-tag (~> 2.8.0)
   jekyll-sitemap (~> 1.4.0)

_config.yml

@@ -19,6 +19,7 @@ plugins:
   - jekyll-redirect-from
   - jekyll-seo-tag
   - jekyll-sitemap
+  - jekyll-feed
 
 sass:
   style:            compressed

_includes/footer.html

@@ -68,6 +68,11 @@
                 {%- include icons/discourse.svg -%}
               </a>
             </li>
+            <li class="list-inline-item ml-1 ml-sm-3">
+              <a href="/feed.xml" rel="noopener" target="_blank" title="RSS/Atom Feed">
+                {%- include icons/rss-fill.svg -%}
+              </a>
+            </li>
           </ul>
         </div>
       </div>

_includes/header.html

@@ -10,6 +10,8 @@
 
   <meta name="referrer" content="strict-origin-when-cross-origin">
 
+  {% feed_meta %}
+
   {%- include head/favicons.html -%}
 
   <link rel="dns-prefetch" href="https://fonts.googleapis.com/">