adding workflow to update website (open-telemetry#1789)

Author: alrex

.github/workflows/docs-update.yml

@@ -0,0 +1,35 @@
+name: Update OpenTelemetry Website Docs
+
+on:
+  # triggers only on a manual dispatch
+  workflow_dispatch:
+
+jobs:
+  update-docs:
+    runs-on: ubuntu-latest
+    steps:
+      - name: checkout
+        uses: actions/checkout@v2
+      - name: make-pr
+        env:
+          API_TOKEN_GITHUB: ${{secrets.DOC_UPDATE_TOKEN}}
+          # Destination repo should always be 'open-telemetry/opentelemetry.io'
+          DESTINATION_REPO: open-telemetry/opentelemetry.io
+          # Destination path should be the absolute path to your language's friendly name in the docs tree (i.e, 'content/en/docs/python')
+          DESTINATION_PATH: content/en/docs/python
+          # Source path should be 'website_docs', all files and folders are copied from here to dest
+          SOURCE_PATH: website_docs
+        run: |
+          TARGET_DIR=$(mktemp -d)
+          export GITHUB_TOKEN=$API_TOKEN_GITHUB
+          git config --global user.name austinlparker
+          git config --global user.email austin@lightstep.com
+          git clone "https://$API_TOKEN_GITHUB@github.com/$DESTINATION_REPO.git" "$TARGET_DIR"
+          rsync -av --delete "$SOURCE_PATH/" "$TARGET_DIR/$DESTINATION_PATH/"
+          cd "$TARGET_DIR"
+          git checkout -b docs-$GITHUB_REPOSITORY-$GITHUB_SHA
+          git add .
+          git commit -m "Docs update from $GITHUB_REPOSITORY"
+          git push -u origin HEAD:docs-$GITHUB_REPOSITORY-$GITHUB_SHA
+          gh pr create -t "Docs Update from $GITHUB_REPOSITORY" -b "This is an automated pull request." -B main -H docs-$GITHUB_REPOSITORY-$GITHUB_SHA
+          echo "done"