Add GitHub icon and rename Facebook & Twitter icons (capitalize)

Author: marla-singer

organizations/client/profile/header/social-media-icons/social-media-icons.html

@@ -11,15 +11,15 @@
         {{# if facebook }}
         <li>
           <a href="{{ facebook }}" target="_blank" class="social-media-link">
-            <img src="/img/social-media-icons/facebook.png" alt="Facebook icon" class="social-media-icon">
+            <img src="/img/social-media-icons/Facebook.png" alt="Facebook icon" class="social-media-icon">
           </a>
         </li>
         {{/ if }}
         <!-- twitter icon -->
         {{# if twitter }}
         <li>
         <a href="{{ twitter }}" target="_blank" class="social-media-link">
-          <img src="/img/social-media-icons/twitter.png" alt="Twitter icon" class="social-media-icon">
+          <img src="/img/social-media-icons/Twitter.png" alt="Twitter icon" class="social-media-icon">
         </a>
         </li>
         {{/ if }}