docs: add linux.do friend badge

Author: Ariestar

README.md

@@ -16,6 +16,7 @@
   <a href="https://github.com/Ariestar/sivtr/actions/workflows/rust.yml"><img alt="CI" src="https://img.shields.io/github/actions/workflow/status/Ariestar/sivtr/rust.yml?branch=main&style=flat-square"></a>
   <a href="LICENSE"><img alt="License" src="https://img.shields.io/badge/license-Apache--2.0-blue?style=flat-square"></a>
   <a href="rust-toolchain.toml"><img alt="Rust" src="https://img.shields.io/badge/rust-1.88%2B-orange?style=flat-square"></a>
+  <a href="https://linux.do/"><img alt="linux.do" src="https://img.shields.io/badge/friend-linux.do-1f883d?style=flat-square"></a>
 </p>
 
 <p align="center">

README.zh-CN.md

@@ -16,6 +16,7 @@
   <a href="https://github.com/Ariestar/sivtr/actions/workflows/rust.yml"><img alt="CI" src="https://img.shields.io/github/actions/workflow/status/Ariestar/sivtr/rust.yml?branch=main&style=flat-square"></a>
   <a href="LICENSE"><img alt="License" src="https://img.shields.io/badge/license-Apache--2.0-blue?style=flat-square"></a>
   <a href="rust-toolchain.toml"><img alt="Rust" src="https://img.shields.io/badge/rust-1.88%2B-orange?style=flat-square"></a>
+  <a href="https://linux.do/"><img alt="linux.do" src="https://img.shields.io/badge/friend-linux.do-1f883d?style=flat-square"></a>
 </p>
 
 <p align="center">