Mermaid Quick Test Page

# Mermaid quick test and demo pages

Some of these pages have duplicates; some are slow to load because they have so many graphs.

If you'd like to clean up one of the pages, please feel free to submit a pull request (PR).

- ## C4 Context

- ## Class diagrams

- ## Data flow charts

- ## Entity Relation diagram

- ## Flow charts

- ## Gantt

- ## Git

- ## Journey

- ## Pie

- ## Requirements

- ## Sequence

- ## State