github url add

Author: beneapp

docs/_includes/social_icons.html

@@ -1,6 +1,6 @@
 <!-- Social Icons -->
 <ul class="icons">
-  {%- if site.twitter_url -%}
+  {%- if site.github_url -%}
   <li><a href="{{- site.github_url -}}" class="icon fa-github"><span class="label">Github</span></a></li>
   {%- endif -%}
   {%- if site.twitter_url -%}