更新 README 和关于页面，调整 Node.js 版本切换步骤并添加认证信息部分

Author: hippieZhou

README.md

@@ -18,14 +18,20 @@
 git clone https://github.com/hippieZhou/hippiezhou.github.io.git
 cd hippiezhou.github.io
 
-# 2. 安装依赖（需要 Node.js 20.x）
+# 2. 使用 nvm 切换到指定 Node.js 版本（推荐）
+nvm use
+# 或者手动指定版本
+# nvm install 20.17.0
+# nvm use 20.17.0
+
+# 3. 安装依赖（需要 Node.js 20.x）
 cd src
 npm install
 
-# 3. 初始化主题子模块
+# 4. 初始化主题子模块
 git submodule update --init --recursive
 
-# 4. 启动开发服务器
+# 5. 启动开发服务器
 npm run server
 # 访问 http://localhost:4000
 ```

src/source/about/index.md

@@ -105,6 +105,12 @@ Anyang Normal University | 2012 – 2016
 
 ---
 
+## 🏆 Certifications
+
+<div data-iframe-width="150" data-iframe-height="270" data-share-badge-id="d2ec554e-fd68-48e0-a70f-03646ca811a5" data-share-badge-host="https://www.credly.com"></div><script type="text/javascript" async src="//cdn.credly.com/assets/utilities/embed.js"></script>
+
+---
+
 ## 🚀 Current Focus
 
 Currently working on **legacy application migration** projects, helping clients transition to **.NET 8** platform while achieving greater business value. Focus areas include: