Verify and update browser versions

[ganicke]

The browser page is updated in response to the conflict described in microsoft/pxt-microbit#3315. Is this the current compatibility matrix? ...

	Edge	Chrome	Safari	Firefox
Windows	Windows 7 Windows 8 Windows 8.1 Windows 10	Windows 7 Windows 8 Windows 8.1 Windows 10	--	Windows 7 Windows 8 Windows 8.1 Windows 10
Mac	--	OS X 10.9 Mavericks OS X 10.10 Yosemite OS X 10.11 El Capitan macOS 10.12 Sierra	OS X 10.9 Mavericks OS X 10.10 Yosemite OS X 10.11 El Capitan macOS 10.12 Sierra	OS X 10.9 Mavericks OS X 10.10 Yosemite OS X 10.11 El Capitan macOS 10.12 Sierra
iOS	Current version	Current version	Current version	--
Android	Current version	Current version	--	--
Linux	--	Recent distribution with latest browser version*	--	Recent distribution with latest browser version*
Chrome OS	--	Version 70 or higher	--	--

* For Raspberry Pi, please see the documentation here.