Markdown Syntax

OneDev supports GitHub flavored markdown, with some additions:

1. Chart with Mermaid, for instance:

   ```mermaid
   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 prevail!
       John-->>Alice: Great!
       John->>Bob: How about you?
       Bob-->>John: Jolly good!
   ```

2. Math equations with Katex, for instance:

   ```math
   \def \x {\mathbf{x}}
   \def \w {\omega}
   \def \d {\operatorname{d}\!}
   P(\x,\w) = \oint_{\partial V} D(\x_0,\w) G(\x-\x_0,\w) \d A(\x_0)
   ```