Angular docs: Suggest es7/array polyfill for hash-based routing

[rmorrise]

I'm submitting a...

[x] Documentation issue or request

Current behavior

Using hash-based routing strategy in IE11, angular throws an error:
IE11 - Object doesn't support property or method 'includes' - javascript window.location.hash

The solution is to add the es7/array polyfill to polyfills.ts:
https://stackoverflow.com/a/52630710/166850

Expected behavior

Please add this polyfill to the table of polyfills in the Angular documentation.

Minimal reproduction of the problem with instructions

What is the motivation / use case for changing the behavior?

Environment

Angular version: 6.0.0


Browser:
- [ ] Chrome (desktop) version XX
- [ ] Chrome (Android) version XX
- [ ] Chrome (iOS) version XX
- [ ] Firefox version XX
- [ ] Safari (desktop) version XX
- [ ] Safari (iOS) version XX
- [x] IE version 11
- [ ] Edge version XX
 
Others:

[jenniferfell]

https://angular.io/guide/browser-support#suggested-polyfills

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