Support for rendering links inside `dcc.Markdown` as `dcc.Link` for single page dash apps

I use dcc.Markdown really extensively in dash-docs. It’s great! However, a few things would make my life a lot easier:

1. (Done!) GitHub style language tags, that is:

``python
def dash():
     pass

Edit - This has been done!

1. Ability for the hyper links to use dcc.Link instead of the HTML link

Currently, I have to break out my dcc.Link from dcc.Markdown, which is pretty tedious: https://github.com/plotly/dash-docs/blob/58b6f84f2d8012d1ae686f1379f326a292370ee3/tutorial/getting_started_part_2.py#L260-L269

1. (Done!) Automatic dedenting. Right now, I use textwrap.dedent everwhere in my text. If I don’t use dedent, then the markdown is formatted as code (4 indents in markdown is code). It would be nice if I could just pass in dedent=True or something

Edit - This has been done!

[alexcjohnson]

Can we find a way to expose this within the markdown syntax, rather than having a prop to decide for all relative links in that component? Would be nice, for folks hosting multiple dash apps on the same domain for example, if each link decided that on its own.

What about prefixing the url with a special character? so [Other app](/app2) would be a regular <a> but something like [Other page](%/page-2) would be a <Link>?

[Marc-Andre-Rivet]

I wonder if this is sufficient and whether all Markdown libraries expose syntax extensions / augmentations https://github.com/jonschlinkert/remarkable/blob/master/docs/plugins.md

Parsing rules are divided into three differents kind of rules (core, block and inline).