add sync-docs workflow (#728)

* add sync-docs workflow

* remove outdated comment

Author: Rich-Harris

.github/workflows/sync-docs.yml

@@ -0,0 +1,29 @@
+name: Sync docs
+
+on:
+  repository_dispatch:
+    types: [sync-request]
+
+jobs:
+  log:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: pnpm/action-setup@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: pnpm
+      - run: pnpm install --frozen-lockfile
+
+      - name: Sync
+        run: cd apps/svelte.dev && pnpm sync-docs -p ${{ github.event.client_payload.package }}
+
+      - name: Create or update pull request
+        uses: peter-evans/create-pull-request@v7
+        with:
+          commit-message: sync ${{ github.event.client_payload.package }} docs
+          title: Sync ${{ github.event.client_payload.package }}
+          body: This is an automated pull request
+          branch: sync:${{ github.event.client_payload.package }}
+          base: main