build(pandoc_extra.yml): add example of deployment

An example how to use docker image pandoc-extra is added.  This
commit equally addresses issue #40.

#40

Signed-off-by: Norwid Behrnd <[email protected]>

Author: nbehrnd

.github/workflows/pandoc_extra.yml

@@ -0,0 +1,24 @@
+name: Usage Pandoc-Extra
+
+on: push
+
+jobs:
+  convert_via_pandoc:
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@v4
+      - name: create output folder
+        run: |
+          mkdir output
+      - uses: docker://pandoc/extra:3.8
+        with:
+          args: >-  # break string of arguments into multiple lines
+            README.md --output=output/README.pdf
+            --standalone
+            --template /.pandoc/templates/eisvogel.latex
+            --listings
+            -V block-headings
+      - uses: actions/upload-artifact@v4
+        with:
+          name: output
+          path: output