Fixed Twitter share link

Twitter share link used github username, not twitter username.

Author: mehmandarov

_includes/author.html

@@ -8,7 +8,7 @@ <h4 class="name">{{ site.name }}</h4>
         <p class="bio">{{ site.bio }}</p>
 
         <div class="share">
-            <a class="twitter" href="https://twitter.com/intent/tweet?text={{ site.url }}{{ page.url }} - {{ page.title }} by @{{ site.github }}">
+            <a class="twitter" href="https://twitter.com/intent/tweet?text={{ site.url }}{{ page.url }} - {{ page.title }} by @{{ site.twitter }}">
                 <svg class="icon icon-twitter"><use xlink:href="#icon-twitter"></use></svg><span class="icon-twitter">Tweet</span>
             </a>