Support for Vimwiki syntax

[pheeria]

Hi 🖖

I'm using Vimwiki and after creating a repo to store my wikifiles I've found out that GitHub partially supports syntax highlighting for .wiki extension. Some amount of research led me hereto.
Unfortunately, there are a couple of problem with the existing highlighting:

• it collapses lists defined with a hyphen - into a single line, unless there is an empty line
• it ignores the code blocks completely (i.e. GitHub doesn't render anything) when they are defined with {{{language }}} syntax like:

{{{python
print("Hello, World!")
}}}

Are you accepting PRs and if yes, do you have any recommendations on how to approach this problem?

Cheers,
Olzhas