add mermaid flowchart to elements page

exampleSite/content/english/pages/elements.md

@@ -192,6 +192,15 @@ s = "Python syntax highlighting"
 print s
 ```
 
+```mermaid
+flowchart TD
+    A[Start] --> B{Is it?}
+    B -- Yes --> C[OK]
+    C --> D[Rethink]
+    D --> B
+    B -- No ----> E[End]
+```
+
 <hr>
 
 ### Blockquote