feat: code samples for component demos

[WillsterJohnson]

I was looking through the site and couldn't find a guide as to exactly how to use this lib in code, so I just read the source code of the cards on the site.

Then I thought, "this code would be a perfect demo if you trimmed out the logic for the demo app", so I did just that and added it to the homepage.

This was more an exercise for me to get familiar with the library than anything else, but having already written it anyway I figured I'd clean up my work and offer it as a PR.

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sample of the new button added to homepage cards:

sample of the dialog opened by the above button:

wider view of the page, dialog open:

[KTibow]

neat, i'll move around the code button and add a copy button soon, but first: