get rid of other absolute path

Author: Justin Martin

index.html

@@ -13,7 +13,7 @@
         <h1>{} Json Diff</h1>
       </div>
       <div class="right">
-        <a href="https://github.com/justspamjustin/online-json-diff"><img src="/img/gh.png"/></a>
+        <a href="https://github.com/justspamjustin/online-json-diff"><img src="img/gh.png"/></a>
 
       </div>
     </header>