Notes on browser compatibility for Try it! page

[ross-spencer]

From searching for a signature:

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### Browser compatibility

One limitation of the WASM build of Siegfried and Roy is that it doesn't work
in Firefox and Safari because of differing levels of support for the
HTML File Picker.

It should work in Chrome, Edge, Opera, and a handfule of other browsers.

If you experience any difficulties, check out Mozilla's resource on
[browser compatibility][mozilla-1].

[mozilla-1]: https://developer.mozilla.org/en-US/docs/Web/API/Window/showOpenFilePicker#browser_compatibility

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