Add link, image, video, formula to the formats array example

[benbro]

Users often ask for a list of all available formats as array and HTML.
I suggest to also expand the HTML example with all available formats similar to the formats page (not in this PR)

Should we also add inline-code and check list?

'code'
{ 'list': 'check' }

[luin]

Looks like code and code-block have the same icon so not sure we should include it for the reason.

[benbro]

What about { 'list': 'check' }? Is it officially supported? I don't see it in the docs.

[luin]

Yeah we can add check. It's officially support but guess there's indeed a lack of documentation.