SequenceDiagram 时序图/序列图
基于SequenceDiagram.js:
http://bramp.github.io/js-sequence-diagrams/
####开启 SequenceDiagram 时序图/序列图支持 配置项: { sequenceDiagram : true } ####示例 ```seq A->B: Message ``` ```seq Andrew->China: Says Hello Note right of China: China thinks\nabout it China-->Andrew: How are you? Andrew->>China: I am good thanks! ```