Add scripts for integration test setup and docs generation

* Add an OpenPGP test keypair.
 * Move script parts of documentation into script, so they can be used on a fresh Ubuntu 20.04 system
   for within a github action to setup a csaf_provider and upload documents to it for an integration test.
 * Use dineshsonachalam/markdown-autodocs in github action to automatically
   insert lines from the scripts into the docs.

Co-authored-by: Bernhard Reiter <bernhard@intevation.de>

.github/workflows/generate-markdown.yml

@@ -0,0 +1,19 @@
+name: generate-markdown
+
+on:
+  push:
+    branches:
+      - "main"
+      - "build-scripts"
+  pull_request:
+    branches:
+      - "main"
+jobs:
+  auto-update-readme:
+      runs-on: ubuntu-latest
+      steps:
+        - uses: actions/checkout@v2
+        - name: Markdown autodocs
+          uses: dineshsonachalam/markdown-autodocs@v1.0.4
+          with:
+            output_file_paths: '[./README.md, ./docs/*.md]'