update white paper link

ricopearl · ricopearl · commit 26231cbc1208 · 2018-01-05T19:36:48.000+08:00
diff --git a/README.md b/README.md
@@ -12,7 +12,7 @@ We will open the source code in May 2018 according to the planned road map.
 
 [Official Website](https://pearlwallet.io)
 
-[White paper]()
+[White paper](https://github.com/PearlWallet/Document/blob/master/PearlWallet_White_Paper_EN.pdf)
 
 RoadMap:
 
