Adding Syntax highlighting

[Dev-iL]

Hello Revath, Let me start by saying thank you for this tool!

I noticed that unlike markdown previews on GitHub "itself", which have syntax highlighting for fenced code blocks, when previewing with this tool we get no colors at all.

I assume that using GitHub's highlighting system is not possible since it requires some server-side actions (e.g. invoking Pygments), but there might be another way, which is what they use on StackOverflow - https://github.com/google/code-prettify.

Can this functionality be added?

[revathskumar]

@Dev-iL Thanks for your kind words. As of now I am not familiar with code-prettify. If you can raise a PR adding this functionality. I am happy to merge it.