Adding missing documentation module

Author: jgebal

.github/workflows/build_pages.yml

@@ -18,6 +18,7 @@ jobs:
         run: |
           pip install mkdocs-material
           pip install mkdocs-git-revision-date-localized-plugin
+          pip install mkdocs-include-markdown-plugin
           pip install mike
       - name: Build website
         run: mkdocs gh-deploy --verbose