add diagrams

mkdocs.yml

@@ -56,7 +56,11 @@ markdown_extensions:
   - pymdownx.keys
   - pymdownx.mark
   - pymdownx.smartsymbols
-  - pymdownx.superfences
+  - pymdownx.superfences: 
+      custom_fences:
+        - name: mermaid
+          class: mermaid
+          format: !!python/name:pymdownx.superfences.fence_code_format
   - pymdownx.snippets
   - pymdownx.tabbed:
       alternate_style: true