Docs: document how to use autofix.ci (#17215)

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

docs/ci.md

@@ -0,0 +1,34 @@
+---
+id: ci
+title: Run Prettier on CI
+---
+
+## GitHub Actions
+
+To apply autofix for Prettier from GitHub Actions, do the following:
+
+1. Install the [`autofix.ci`](https://github.com/apps/autofix-ci) GitHub App.
+1. Make sure you have a **pinned** version of Prettier installed in your repository.
+1. Create `.github/workflows/prettier.yml` with following content:
+
+   ```yaml title=".github/workflows/prettier.yml"
+   name: autofix.ci
+   on:
+     pull_request:
+     push:
+   permissions: {}
+   jobs:
+     prettier:
+       runs-on: ubuntu-latest
+       steps:
+         - uses: actions/checkout@v4
+         - uses: actions/setup-node@v4
+         - run: |
+             yarn
+             yarn prettier . --write
+         - uses: autofix-ci/action@v1
+           with:
+             commit-message: "Apply Prettier format"
+   ```
+
+For more information see [autofix.ci](https://autofix.ci/) website.