chore: add donation disclaimer

Author: tobyxdd

docs/docs/Donation.md

@@ -8,6 +8,8 @@ Hysteria is an open source project born out of a passion to bring value to the c
 
 **We are willing to list anyone who has donated more than $10 as an official sponsor in the Hall of Fame below.** After donating, send an email to d400os4or@mozmail.com with your name and optionally a link and description you would like to display.
 
+**Disclaimer:** Donations to this project are voluntary contributions. We do not assume any obligation nor provide any services or guarantees in return. This project is an open-source software only; you must set up both server and client yourself. There are no official proxies or VPN services, beware of scams. Thank you for your support!
+
 === ":fontawesome-solid-dollar-sign: Stripe"
 
     https://donate.stripe.com/5kAaFx93KbWt11KdQQ

docs/docs/Donation.zh.md

@@ -8,6 +8,8 @@ Hysteria 是一个旨在打破审查高墙的纯公益开源项目。如果你
 
 **我们愿意将任何捐赠超过 $10 的用户/组织列入下面的荣誉榜。** 捐赠后，可以发送邮件至 d400os4or@mozmail.com 提供希望展示的名字，以及可选的链接和一段描述。
 
+**免责声明：**对本项目的捐赠属于自愿行为，我们不因此承担任何形式的义务，也不提供任何服务或保证。本项目仅为开源软件，需自行架设服务端与客户端进行使用，并不提供任何代理或 VPN 服务，请谨防受骗。感谢您的支持！
+
 === ":fontawesome-solid-dollar-sign: Stripe"
 
     https://donate.stripe.com/5kAaFx93KbWt11KdQQ