I could have posed the question better. But, I haven't found one that served my needs yet. Nor do I not know of one that may have interesting features that would make it easier to do things, like maybe adding shields/badges/assets within automatically or being able to create a directory like structure by generating new MD files when wanting to create a comprehensive API doc.
Chances are, your favorite text editor can handle markdown well enough... unless you want WYSIWYG, in which case your text editor would still be good enough for the job and you would be wrong :-)
The following markups are supported. The dependencies listed are required if you wish to run the library. You can also run script/bootstrap to fetch them all.
GNU Emacs of course. I am particularly fond of spacemacs, because I like vim keybindings.
For git functionality we have the excellent magit package on our side, which makes Emacs also my favorite git interface.
VS Code's extension system makes it pretty easy to build your own code snippet extension. I use my own private extension to easily "generate" different types of markdown files (ie readme vs a troubleshooting guide) from my personalized snippets.
A lot of people seem to have misunderstood the question and are offering text editors. Apostrophe as actually looks like it fits the bill for a decent markdown editor, which is what OP seems to have been asking for
Any text editor that can edit markdown files with syntax highlighting? What kind of git functionality do you want? If you want to see the formatting in place as you edit, look for a WYSIWYG editor (Ghostwriter and Typora come to mind). I use Neovim and have lazygit opened in another terminal tab.
I just use whatever text editor I happen to have open - generally that's (neo)vim for me, but I've also used IntelliJ/JetBrains products to do so, along with VSCode on the rare case.
None of them have had the extra features that you mentioned, I don't use emacs but considering its very powerful org-mode I wouldn't be surprised if someone has implemented something similar for Markdown? I haven't specifically seen anything that covers these though (which could just be not looking hard enough, admittedly).
More like a notes/personal wiki app, than a readme editor.
That said, Obsidian is a diamond in the rough. Building a personal wiki while learning a skill and referencing it later (via search or category) is a true life hack. It feels like augmenting your memory capacity.
Truly invaluable if you need to reference things often but your knowledge base is highly specialized (e.g., I'm a neurology professor)