docs(README): add new “Prerequisites” section under the existing “How to Use” heading and before the CLI subsection. (alibaba#261)

Author: skate29

README.md

@@ -92,6 +92,10 @@ The agent's strengths are concentrated where they matter most — dynamic decisi
 
 ## How to Use
 
+### Prerequisites
+
+- **Git >= 2.38** — Open Code Review relies on Git for diff generation, code search, and repository operations.
+
 ### CLI
 
 #### Install

README.zh-CN.md

@@ -92,6 +92,10 @@ Open Code Review 的核心设计理念是将确定性工程与 Agent 结合，
 
 ## 如何使用
 
+### 前置条件
+
+- **Git >= 2.38** — Open Code Review 依赖 Git 进行 diff 生成、代码搜索和仓库操作。
+
 ### CLI
 
 #### 安装