Update header.html

docs/_includes/header.html

@@ -1,6 +1,6 @@
       <header>
         <div id="banner">
-          <div class="pull-left"><a href="https://shimingxy.github.io/MaxKey/" id="bannerLeft"><img src="https://github.com/shimingxy/MaxKey/blob/master/images/logo.jpg"  alt=""/></a></div>
+          <div class="pull-left"><a href="https://shimingxy.github.io/MaxKey/" id="bannerLeft"><img src="https://github.com/shimingxy/MaxKey/blob/master/logo.jpg?raw=true"  alt=""/></a></div>
           <!--<div class="pull-right"><a href="" id="bannerRight"><img src="images/logo.png"  alt=""/></a></div>-->
           <div class="clear"><hr/></div>
         </div>