fix: 修正 mdBook 构建路径，确保正确上传文档

Author: AptS-1547

.github/workflows/mdbook.yaml

@@ -44,11 +44,13 @@ jobs:
         id: pages
         uses: actions/configure-pages@v5
       - name: Build with mdBook
-        run: mdbook build
+        run: |
+          cd docs
+          mdbook build
       - name: Upload artifact
         uses: actions/upload-pages-artifact@v3
         with:
-          path: ./book
+          path: ./docs/book
 
   # Deployment job
   deploy: