content: Google Fonts integration / local hosting

### URL

https://ionicframework.com/docs/v3/api/components/typography/Typography/

### Issue Description

Ionic Framework uses a Google Font (`Roboto`), however, the default build doesn't include the font.

It would be nice if the documentation also explains how to host the Google Fonts used by Ionic (and other ones)
(local hosting would be important for GDPR compliance).

What can be used for this? A webpack loader? An ionic script?