Plug-In Resources

@uranusjr is already working on this.

Since Dec 1, 2018.

Hello, friends.

I've written two new resources that I want to share with the community:

* **[Thesi](https://github.com/chriszielinski/Thesi) 🧝‍♀️** — A MacDown convenience plug-in, written in Swift. It beautifies headings and offers shorthand syntax for callouts, images, and links.
* **[Swift MacDown Plug-In](https://github.com/chriszielinski/MacDown-Swift-Plug-In)** — An xcode-template & guide to creating your own swift MacDown plug-in. It also includes an incomplete Swift wrapper around `MPDocument` that includes `updateEditorMarkdown(string:)`, which supports user undo-ing and refreshes the Markdown syntax highlighting (partially solves issues raised in #758).

I'm bummed to see that the plug-in developer community is non-existent, or at least in-hiding. It'd be great to have some central resource for plug-in discovery. It goes without saying that a plug-in manager (#752) would be no trivial undertaking, so may I propose an [_Awesome MacDown Plug-Ins_](https://github.com/chriszielinski/awesome-macdown-plug-ins) repository—at least for the time being. I've already created the repo, but I think it would feel most at home (& get the best exposure) under the [_MacDownApp_](https://github.com/MacDownApp) GitHub organization. So I'd like to transfer it over. Let me know.