feat: explore markdown-rs

[zeon256]

Currently there are 3 popular markdown parser that are available in rust all of which offer their own set of pros/cons

• comrak
• markdown-rs
• pulldown_cmark

This issue is a tracking issue for evaluating markdown-rs. Currently, this is implemented in the branch feat/markdown-rs

Findings

• When rendering progit.md without syntax highlighting, it takes about 150ms as compared to 18ms compared to comrak
• Not exactly sure how to add syntax highlighting, but since it exposes mdast, the direction for that would probably be using the AST and applying it ourselves
• This issue on markdown-rs contains discussion on plugins
• This library might actually the way forward since it can expose the AST which can allow us to do more processing