Document markdown myst usage

[jacopok]

Hello, I've tried using this extension in conjunction with myst and it works well; for example, the effect of the rst command

:cite:p:`1987:nelson`

can be equivalently obtained in a markdown file as

{cite:p}`1987:nelson`

My guess is that this generalizes; it would be nice to briefly mention it in the README, since it's a simple thing but it might leave a user confused regarding the correct syntax (it did for me).

[mcmtroffaes]

Thanks, that's a great suggestion!

[mcmtroffaes]

Could you double check this example (to be added to the docs)?

    See {cite:p}`1987:nelson` for an introduction to non-standard analysis.

    ```{bibliography} references.bib
    ``` 

[jacopok]

I tried your example verbatim and it is working for me, thanks!
Renders as

with the furo theme.

[mcmtroffaes]

Awesome, many thanks for the quick turnaround!