Custom highlight

[zRains]

Is your feature request related to a problem? Please describe.

no

Describe the solution you'd like

If the highlight function is passed in options: MarkdownOptions, this function will be invoked, otherwise the default will be used.

 const md = MarkdownIt({ 
   html: true, 
   linkify: true, 
   highlight: options.highlight || await highlight(options.theme), 
   ...options 
 }) as MarkdownRenderer 

Describe alternatives you've considered

No response

Additional context

No response

Validations

• Follow our Code of Conduct
• Read the docs.
• Read the Contributing Guidelines.
• Check that there isn't already an issue that asks for the same feature to avoid creating a duplicate.

[kiaking]

Yeah why not. I think this can be useful, and simple to implement. If anyone wants to tackle this, PR is welcome!