add PayPal info

README.md

@@ -157,7 +157,8 @@ You could help VNote's development in may ways.
 - Spread and promote VNote to your friends. Popularity is a strong power to drive developers.
 - Participate in the development of VNote and send PullRequest to make VNote perfect.
 - Last, really appreciate your donate to VNote if you think VNote really helps you and you want to help VNote.
-    - Alipay: [email protected]  
+    - PayPal: [PayPal.Me/vnotemd](https://www.paypal.me/vnotemd)
+    - Alipay: `[email protected]`  
     ![Alipay](screenshots/alipay.png)
 
 # Dependencies

README_zh.md

@@ -160,7 +160,8 @@ VNote中，几乎一切都是可以定制的，例如背景颜色、字体以及
 - 向您的朋友们推广和传播VNote。普及度是驱动开发者的一股强大力量。
 - 参与到VNote的开发中，发送PullRequest来帮助VNote变得更完美。
 - 最后，非常感谢您的捐赠如果您觉得VNote真的帮助到您并且想回馈VNote。
-    - 支付宝: [email protected]  
+    - PayPal: [PayPal.Me/vnotemd](https://www.paypal.me/vnotemd)
+    - 支付宝: `[email protected]`  
     ![Alipay](screenshots/alipay.png)
 
 # 依赖