Use fancy github information and warning sections in scarpet docs

[altrisi]

Note

This has a nice line at the left

Warning

This also has, but a different color!

Important

Not only that, they also have tiny icons next the title

One use case is for marking deprecated functions.

Maybe also on wiki pages if it makes sense in any.

[altrisi]

Trying it, I don't like it that much, it looks out of place.