Mermaid is a tool that lets you generate flow charts, sequence diagrams, gantt charts, class diagrams and vcs graphs from a simple markup language. This means you can embed these directly in the source rather than creating an image with some external tool and then checking it into the tree. To add a diagram, simply put something like this into your page:
.. mermaid:: graph TD; A-->B; A-->C; B-->D; C-->D;
The result will be:
sequenceDiagram participant Alice participant Bob Alice->>John: Hello John, how are you? loop Healthcheck John->>John: Fight against hypochondria end Note right of John: Rational thoughts <br/>prevail! John-->>Alice: Great! John->>Bob: How about you? Bob-->>John: Jolly good!
See mermaid’s official docs for more details on the syntax.