Update 2018 reward picture
diff --git a/assets/images/rewards/2018_oschina.jpg b/assets/images/rewards/2018_oschina.jpg
index 25612bd..911c0c0 100644
--- a/assets/images/rewards/2018_oschina.jpg
+++ b/assets/images/rewards/2018_oschina.jpg
Binary files differ