- Remove Opera from the Android/iOS listing - it was not clear if this referred to Opera Mobile or Opera Mini. If the former, it's only available on Android, and uses Blink the same way that Chrome does, so it's supported. If the latter, it's worth expanding that in general we don't support proxy browsers
- Add proxy browser note
- Change Firefox/iOS from N/A to Supported (as it uses standard iOS web view) - closes https://github.com/twbs/bootstrap/issues/18602
- Remove Win/Safari, as there's not been any viable version since 2012