docs(readme): Improve online demo section formatting

- Add line breaks to online demo section in both README files
- Enhance readability of demo URL presentation
- Maintain consistent formatting across Chinese and English README documents

README.md

@@ -36,7 +36,9 @@
 
 #### 🌐 在线演示
 
-无需部署，直接访问在线演示（数据存储在浏览器本地，支持所有核心功能）：**[https://xcodereviewer-preview.vercel.app](https://xcodereviewer-preview.vercel.app)**
+无需部署，直接访问在线演示（数据存储在浏览器本地，支持所有核心功能）：
+
+**[https://xcodereviewer-preview.vercel.app](https://xcodereviewer-preview.vercel.app)**
 
 ## 🌟 为什么选择 XCodeReviewer？
 

README_EN.md

@@ -36,7 +36,9 @@
 
 #### 🌐 Online Demo
 
-No deployment needed, access the online demo directly (data stored locally in browser, all core features supported): **[https://xcodereviewer-preview.vercel.app](https://xcodereviewer-preview.vercel.app)**
+No deployment needed, access the online demo directly (data stored locally in browser, all core features supported):
+
+**[https://xcodereviewer-preview.vercel.app](https://xcodereviewer-preview.vercel.app)**
 
 ## 🌟 Why Choose XCodeReviewer?