TEZ-4332: Change ASF logo on Tez webpage according to recent guidelines (#148)

diff --git a/docs/src/site/site.xml b/docs/src/site/site.xml
index c8e6479..5964cbc 100644
--- a/docs/src/site/site.xml
+++ b/docs/src/site/site.xml
@@ -47,8 +47,8 @@
 
   <bannerRight>
     <name>Apache Software Foundation</name>
-    <src>http://www.apache.org/images/asf_logo.gif</src>
-    <href>http://www.apache.org/</href>
+    <src>https://apache.org/foundation/press/kit/asf_logo_wide.png</src>
+    <href>https://www.apache.org/</href>
   </bannerRight>
 
   <publishDate position="right"/>