https://github.blog/2022-02-14-include-diagrams-markdown-files-mermaid/
https://mermaid-js.github.io/mermaid/#/n00b-syntaxReference?id=syntax-structure
sequenceDiagram
participant dotcom
participant iframe
participant viewscreen
dotcom->>iframe: loads html w/ iframe url
iframe->>viewscreen: request template
viewscreen->>iframe: html & javascript
iframe->>dotcom: iframe ready
dotcom->>iframe: set mermaid data on iframe
iframe->>iframe: render mermaid
erDiagram
CUSTOMER }|..|{ DELIVERY-ADDRESS : has
CUSTOMER ||--o{ ORDER : places
CUSTOMER ||--o{ INVOICE : "liable for"
DELIVERY-ADDRESS ||--o{ ORDER : receives
INVOICE ||--|{ ORDER : covers
ORDER ||--|{ ORDER-ITEM : includes
PRODUCT-CATEGORY ||--|{ PRODUCT : contains
PRODUCT ||--o{ ORDER-ITEM : "ordered in"