docs: remove v2 example

Author: peaceiris

README.md

@@ -33,23 +33,6 @@ The next example step will deploy `./public` directory to the remote `gh-pages`
     publish_dir: ./public
 ```
 
-<details>
-<summary>👉 Old v2 YAML here</summary>
-
-```yaml
-- name: Deploy
-  uses: peaceiris/actions-gh-pages@v2
-  env:
-    ACTIONS_DEPLOY_KEY: ${{ secrets.ACTIONS_DEPLOY_KEY }}
-    # PERSONAL_TOKEN: ${{ secrets.PERSONAL_TOKEN }}
-    # GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-    PUBLISH_BRANCH: gh-pages
-    PUBLISH_DIR: ./public
-```
-
-</details>
-
-
 Three tokens are supported.
 
 | Token | Private repo | Public repo | Protocol | Setup |