Cherry pick: docs: Edited "Features Reference" section in

"<uses-feature>" page.

The "Features Reference" section now lists all hardware and software
features that apps can use on devices running Marshmallow, and some
existing features now have more descriptive examples.

Converted the tables listing hardware and software features to h4
elements and definition lists to make the page more reader-friendly,
particularly on handheld devices.

Bug: 27803596
Change-Id: I3490f5dcde6a838d69940c70e06d9cd2cb8a7bdc