Improve readability of annotation syntaxes

还没有人认领这个 Issue。

The [method currently used](http://localhost:3000/wiki/annotations/#understanding-this-page) for describing how to use annotations can be easy to understand at times:
`---@type `

And also impossible for mere mortals to understand:
`---@cast [+|-][, [+|-]...]`
`---@overload fun([param: type[, param: type...]]): [return_value[,return_value]]`

There must be a better way to represent these more complex syntaxes while also not using symbols regularly in use (`<`, `>`, `(`, `)`, `[`, `]`, `{`, `}`, `@`, `#`, `-`, `+`, `=`, `:`, `"`, `,`, `.`, `?`). Although now that I have listed some in-use symbols, I realize we really are quite limited. It is hard to explain a syntax that uses many symbols… using symbols.

I'm open to any suggestions on how this can be improved 🙂

从链接的 annotations/#understanding-this-page 页面开始，并查看 issue 中展示的复杂语法示例。该 issue 没有定义首选的替代方案或明确的完成测试；要视为完成，需要就一种更易读的表示法达成一致，并更新文档示例。

由索引模型根据 Issue 内容生成。