Update README

README.md

@@ -128,6 +128,53 @@ This configuration will create pull requests that look like this:
 
 ![Pull Request Example](https://github.com/peter-evans/create-pull-request/blob/master/pull-request-example.png?raw=true)
 
+
+### Example usage with 'on: pull_request' workflows
+
+The following is an example workflow for a use-case where [autopep8](https://github.com/peter-evans/autopep8) action runs as both a check on pull requests and raises a further pull request to apply code fixes.
+
+How it works:
+1. When a pull request is raised the workflow executes as a check
+2. If autopep8 makes any fixes a pull request will be raised for those fixes to be merged into the current pull request branch. The workflow then deliberately causes the check to fail.
+3. When the pull request containing the fixes is merged the workflow runs again. This time autopep8 makes no changes and the check passes.
+4. The original pull request can now be merged.
+
+```yml
+name: autopep8
+on: pull_request
+jobs:
+  autopep8:
+    if: startsWith(github.head_ref, 'autopep8-patches') == false
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v1
+      - name: autopep8
+        id: autopep8
+        uses: peter-evans/autopep8@v1.1.0
+        with:
+          args: --exit-code --recursive --in-place --aggressive --aggressive .
+      - name: Set autopep8 branch name
+        id: vars
+        run: echo ::set-output name=branch-name::"autopep8-patches/$GITHUB_HEAD_REF"
+      - name: Create Pull Request
+        if: steps.autopep8.outputs.exit-code == 2
+        uses: peter-evans/create-pull-request@v1.5.2
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          COMMIT_MESSAGE: autopep8 action fixes
+          COMMIT_AUTHOR_EMAIL: peter-evans@users.noreply.github.com
+          COMMIT_AUTHOR_NAME: Peter Evans
+          PULL_REQUEST_TITLE: Fixes by autopep8 action
+          PULL_REQUEST_BODY: This is an auto-generated PR with fixes by autopep8.
+          PULL_REQUEST_LABELS: autopep8, automated pr
+          PULL_REQUEST_REVIEWERS: peter-evans
+          PULL_REQUEST_BRANCH: ${{ steps.vars.outputs.branch-name }}
+          BRANCH_SUFFIX: none
+      - name: Fail if autopep8 made changes
+        if: steps.autopep8.outputs.exit-code == 2
+        run: exit 1
+```
+
 ### Dynamic configuration using variables
 
 The following examples show how configuration for the action can be dynamically defined in a previous workflow step.