fix workflow

Author: 胡闰智

.github/workflows/deploy.yml

@@ -26,7 +26,9 @@ jobs:
           pip install mkdocs-material
 
       - name: Build site
-        run: mkdocs build
+        run: |
+          cd docs
+          mkdocs build
 
       - name: Deploy to GitHub Pages
         uses: peaceiris/actions-gh-pages@v3