Add patch for Mermaid support

mkdocs.yml

@@ -25,6 +25,7 @@ extra_css:
 extra_javascript:
   - https://cdnjs.cloudflare.com/ajax/libs/tablesort/5.2.1/tablesort.min.js
   - javascripts/tables.js
+  - https://unpkg.com/mermaid/dist/mermaid.min.js
 
 markdown_extensions:
   - toc:
@@ -39,10 +40,19 @@ markdown_extensions:
   - abbr
   - pymdownx.snippets
   - pymdownx.highlight
-  - pymdownx.superfences
+  - pymdownx.superfences:
+      # make exceptions to highlighting of code:
+      custom_fences:
+        - name: mermaid
+          class: mermaid
+          format: !!python/name:mermaid2.fence_mermaid
+
 
 plugins:
   - git-revision-date
+  - mermaid2:
+      arguments:
+        theme: 'dark'
 
 extra:
   social: