fix typo in CI for build api doc

.github/workflows/build-doc.yml

@@ -22,4 +22,10 @@ jobs:
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
           publish_dir: ./os/target/riscv64gc-unknown-none-elf/doc
-          destination_dir: ${{ github.ref_name }}
+          destination_dir: ./public/${{ github.ref_name }}
+      - name: Deploy index.html to Github Pages
+        uses: peaceiris/actions-gh-pages@v3
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          publish_dir: ./public
+          destination_dir: ./public   

public/index.html

@@ -25,6 +25,7 @@
 <h1><a href="./ch7/os/index.html">7. IPCOS API doc</a></h1>
 <h1><a href="./ch8/os/index.html">8. SyncMutexOS API doc</a></h1>
 <h1><a href="./ch9/os/index.html">9. DeviceOS API doc</a></h1>
+<h1><a href="./main/os/index.html">10. main-branch OS API doc</a></h1>
 </body>
 
 </html>