feat: Add workflow to detect changes in dot org (#854)

* feat: Add new workflow for detecting changes in dot org
* Refactor to use a new dep for making PR
* Use better change comparision command to detect changes
* Added paths to git add the generated files + yaml

---------

Co-authored-by: Michael McKeen <[email protected]>

Author: lamATnginx

.github/workflows/dot-org-content.yml

@@ -0,0 +1,56 @@
+name: Detect changes in documentation within nginx/nginx.org
+
+on:
+  schedule:
+    - cron: "0 */23 * * *"
+permissions:
+  contents: write
+  pull-requests: write
+  issues: write
+
+jobs:      
+  detect-changes:
+    name: Detect changes in 'en' docs of nginx/nginx.org
+    runs-on: ubuntu-latest
+    outputs:
+      IS_CHANGES_DETECTED: ${{ steps.check_changes.outputs.changed }}
+    steps: 
+      - name: Checkout Repository
+        uses: actions/checkout@85e6279cec87321a52edac9c87bce653a07cf6c2 # v4.2.2
+        with:
+          fetch-depth: 0
+      - name: Clone the nginx/nginx-org repository
+        run: |
+            git clone --depth=2 https://github.com/nginx/nginx.org.git dot-org-repo
+      - name: Check for changes in xml/en folder
+        id: check_changes
+        run: |
+            cd dot-org-repo
+
+            if git whatchanged --since="1 day ago" -- _xml/en/; then
+              echo "Changes detected in /en"
+              echo "changed=true" >> $GITHUB_OUTPUT
+            else
+              echo "No changes in /en"
+              echo "changed=false" >> $GITHUB_OUTPUT
+            fi
+      - name: Execute make target 'make hugo-md' to generate markdown
+        if: steps.check_changes.outputs.changed == 'true'
+        run: |
+            cd dot-org-repo
+            make module-markdown
+      - name: Create PR 
+        uses: peter-evans/create-pull-request@v7
+        if: steps.check_changes.outputs.changed == 'true'
+        with:
+          commit-message: "chore: Update nginx plus module reference from detected changes in nginx/nginx.org"
+          labels: product/nginx-plus, dependencies, module-reference
+          base: main
+          branch: update-nginx-module-ref
+          title: 'NGINX Plus - Module Ref: Update content for content/nginx due to detected changes'
+          add-paths: |
+            dot-org-repo/libxslt-md/
+            dot-org-repo/yaml/nginx_api.yaml
+          body: |
+            ### Proposed Changes
+            Updated NGINX Plus docs.