Demo doesn't run in Internet Explorer

There are two known issues in Internet Explorer (IE):
1. IE [lacks native Promise support](https://caniuse.com/#search=promise), so you need to add a promise polyfill to get the demo to work in IE.

2. IE tries to download the JSON from the mock API at localhost:3001/users. [Here are some workarounds](https://stackoverflow.com/questions/6114360/ie-prompts-to-open-or-save-json-result-from-server).

Start by running the demo in Internet Explorer and inspect how it loads the Promise-dependent code and requests JSON from the mock API at localhost:3001/users. Check the linked Promise support and JSON workaround references, then verify that the demo runs successfully in IE without the download prompt.

Rédigé par le modèle d'indexation à partir du texte de l'issue.