DOC: Add MyST syntax cheatsheet and comparison sheet

Is your feature request related to a problem? Please describe.

Add a user friendly cheatsheet for writing MyST syntax.

It would be great if the cheat sheet could be accompanied by an “example” link in which the same contents are displayed in rst, MyST, latex (and other possible source markup types)

Currently most details for MyST are located in the myst-parser docs but it would be nice to have a concise summary for users at the jupyter-book level as a single stop resource.

@najuzilu would you be willing to take a project like this on?

[jstac]

Thanks for the list @najuzilu . It looks great to me. Others will add more over time.

The target users @thomassargent30 and I had in mind when we suggested a cheat sheet are people getting started with Jupyter Book. The syntax most helpful to such people would be MyST / MyST-NB. For example, code blocks should be

 ```{code-cell} ipython3
 xyz
 ```

Rather than

 ```{code-block} python
 xyz
 ```

The aim is to help people write books in JB easily, not be a pure resource on MyST — that’s better off left to the MyST documentation.

In terms of where we put this, I don’t mind.

Perhaps a good starting point is to make something similar to https://docutils.sourceforge.io/docs/user/rst/quickref.html (but hopefully looking nicer 😃

[choldgraf]

I’m a +1 on two cheat sheets - one for common and useful syntax in MyST, and another for a full comparison (which I’d see as more of an advanced feature…we don’t want to put rST or Latex in front of new users IMO)