Feat: Markdown kit for readme, changelog & code

[WilcoSp]

This pr in specific is only to compare, it won't be merged!

🧭 Context

Currently changelog uses a seperate marked markdown renderer from readme, this pr takes the shared code and makes it into a "markdown kit" so that code that can be shared will be shared

📚 Description

moves shared code for both changelog & readme to a shared markdown kit while still allowing for each to have their unique needs.

Heading have been changed to be more consistent and easier to use by users to the following:

• ## heading -> <hx><a href="#...>heading</a></hx>
• ## [Example](https://example.com) -> <hx><a href="https://example.com">Example</a><a href="#...></a></hx>

[WilcoSp]

I'm done combining the code, for readme the tests are 100% with the only one being changed are for heading.

I'm currently writing tests for changelog's markdown renderer for the things that are different compared to readme.