use actions/setup-node@v2, actions/checkout@v2

.github/workflows/docs.yml

@@ -1,25 +0,0 @@
-name: github-pages
-on:
-  push:
-    branches: [master]
-jobs:
-  main:
-    runs-on: ubuntu-latest
-    env:
-      EMAIL: octocat@github.com
-    steps:
-      - uses: actions/checkout@v1
-      - run: echo "::set-env name=YARN_CACHE_DIR::$(yarn cache dir)"
-      - uses: actions/cache@v1
-        with:
-          path: ${{ env.YARN_CACHE_DIR }}
-          key: yarn-${{ hashFiles('**/yarn.lock') }}
-          restore-keys: yarn-
-      - run: yarn
-      - run: git -c user.name="$(whoami)" subtree add --prefix docs origin gh-pages
-      - run: yarn doc
-      - run: git add -f docs
-      - run: git -c user.name="$(whoami)" commit -m github-pages
-      - run: git remote add github "https://github:${GITHUB_TOKEN}@github.com/${GITHUB_REPOSITORY}.git"
-        env: { GITHUB_TOKEN: "${{ secrets.GITHUB_TOKEN }}" }
-      - run: git subtree push --prefix docs github gh-pages

.github/workflows/github-pages.yml

@@ -0,0 +1,26 @@
+name: github-pages
+on:
+  push:
+    branches: [master]
+jobs:
+  main:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-node@v2
+        with: { node-version: lts/*, cache: yarn }
+      - name: Git config
+        run: |
+          git config user.name bot
+          git config user.email bot@example
+      - name: Build
+        run: |
+          git subtree add --prefix docs origin gh-pages
+          yarn
+          yarn doc
+      - name: Publish
+        run: |
+          git add -f docs
+          if git commit -m update; then
+            git subtree push --prefix docs origin gh-pages
+          fi