Automate Flux upgrades with GitHub Actions

Signed-off-by: Stefan Prodan <stefan.prodan@gmail.com>

action/README.md

@@ -1,6 +1,57 @@
 # Flux GitHub Action
 
-Example workflow:
+Usage:
+
+```yaml
+    steps:
+      - name: Setup Flux CLI
+        uses: fluxcd/flux2/action@main
+      - name: Run Flux commands
+        run: flux -v
+```
+
+### Automate Flux updates
+
+Example workflow for updating Flux's components generated with `flux bootstrap --arch=amd64 --path=clusters/production`:
+
+```yaml
+name: update-flux
+
+on:
+  workflow_dispatch:
+  schedule:
+    - cron: "0 * * * *"
+
+jobs:
+  components:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v2
+      - name: Setup Flux CLI
+        uses: fluxcd/flux2/action@main
+      - name: Check for updates
+        id: update
+        run: |
+          flux install --arch=amd64 \
+            --export > ./clusters/production/flux-system/gotk-components.yaml
+
+          VERSION="$(flux -v)"
+          echo "::set-output name=flux_version::$VERSION"
+      - name: Create Pull Request
+        uses: peter-evans/create-pull-request@v3
+        with:
+            token: ${{ secrets.GITHUB_TOKEN }}
+            branch: update-flux
+            commit-message: Update to ${{ steps.update.outputs.flux_version }}
+            title: Update to ${{ steps.update.outputs.flux_version }}
+            body: |
+              ${{ steps.update.outputs.flux_version }}
+```
+
+### End-to-end testing
+
+Example workflow for running Flux in Kubernetes Kind:
 
 ```yaml
 name: e2e
@@ -23,3 +74,6 @@ jobs:
       - name: Install Flux in Kubernetes Kind
         run: flux install
 ```
+
+A complete e2e testing workflow is available here
+[flux2-kustomize-helm-example](https://github.com/fluxcd/flux2-kustomize-helm-example/blob/main/.github/workflows/e2e.yaml)