在vnote3以后的版本中增加可行的mathjax配置方法（give a convenient way to config mathjax）

[haigear]

Is your feature request related to a problem? Please describe. A clear and concise description of what the problem is. Ex. I'm always frustrated when [...] I'm frustrated when I try to config a new version mathjax in vnote (3.0 or later version) Describe the solution you'd like A clear and concise description of what you want to happen. I want a convenient way to config mathjax in new version of vnote. Describe alternatives you've considered A clear and concise description of any alternative solutions or features you've considered.

Additional context Add any other context or screenshots about the feature request here.

[tamlok]

最新版设置里面不是有吗？