add instagram link on footer

Author: matheusbsilva

_config.yml

@@ -9,6 +9,7 @@ url:                "https://blackrockdigital.github.io"
 twitter_username:   SBootstrap
 github_username:    BlackrockDigital
 facebook_username:  StartBootstrap
+instagram_username:  
 linkedin_username:
 
 # Add your google-analytics ID here to activate google analytics

_includes/footer.html

@@ -57,6 +57,16 @@
             </a>
           </li>
           {% endif %}
+          {% if site.instagram_username %}
+          <li class="list-inline-item">
+            <a href="https://instagram.com/{{ site.instagram_username }}">
+              <span class="fa-stack fa-lg">
+                <i class="fas fa-circle fa-stack-2x"></i>
+                <i class="fab fa-instagram fa-stack-1x fa-inverse"></i>
+              </span>
+            </a>
+          </li>
+          {% endif %}
         </ul>
         <p class="copyright text-muted">Copyright &copy; {{ site.author }} {{ 'now' | date: "%Y" }}</p>
       </div>