Blockquote note and warning support

[xt0rted]

GitHub Flavored Markdown now supports special styling for note and warning blockquotes. community/community#16925

Note
This is a note

Warning
This is a warning

[jjspace]

Just as a note this was a poorly thought out and implemented feature that's no longer documented and could go away at any moment. There's a lot of discussion in that linked thread but many people agree it should not have been added the way it was so I'm not sure it's worth trying to support for this extension. Specifically see this comment thread

[adam-grant-hendry]

It's been a minute and the GitHub Docs now state the beta testing syntax is deprecated and the official syntax is now:

> [!NOTE]
> Highlights information that users should take into account, even when skimming.

> [!IMPORTANT]
> Crucial information necessary for users to succeed.

> [!WARNING]
> Critical content demanding immediate user attention due to potential risks.

Any chance we can reconsider supporting the syntax?

[ShadiestGoat]

I would love this to be added!

As a side note, perhaps this issue should be renamed to include something like "alerts" or "admonitions"?

[to-sta]

Would also like to see this added 😄

[ByPikod]

@ShadiestGoat @adam-grant-hendry @xt0rted

I was looking for this feature and found this repository. I thought I could contribute to this repository by introducing the desired feature. However, I soon realized that the "blockquote note syntax" couldn't be implemented using only CSS within this repository.

As a solution, I developed a MarkdownIt plugin to convert Markdown into HTML. Then, I created a VS Code extension that utilizes this plugin along with a CSS file I wrote. You can find the extension here:
https://marketplace.visualstudio.com/items?itemName=yahyabatulu.vscode-markdown-alert

[uncenter]

Thank you @ByPikod! Works fabulously.