📖 [Docs] Enable mermaid.js (operator-framework#1290)

- Enable mermaid.js via https://squidfunk.github.io/mkdocs-material/reference/diagrams/#configuration

mkdocs.yml

@@ -31,7 +31,11 @@ markdown_extensions:
       pygments_lang_class: true
   - pymdownx.inlinehilite
   - pymdownx.snippets
-  - pymdownx.superfences
+  - pymdownx.superfences:
+      custom_fences:
+        - name: mermaid
+          class: mermaid
+          format: !!python/name:pymdownx.superfences.fence_code_format
   - def_list
   - pymdownx.tasklist:
       custom_checkbox: true