Our March 2016 release includes new sections and updates:
A product is accessible when all people—regardless of ability—can use it. We’ve recently expanded #materialdesign guidelines to serve as a primer and comprehensive resource for accessibility considerations. If you’re responsible for determining accessibility standards for your team, or just interested in improving the accessibility of your product for all users—and who isn't?—this is the place to start.
There’s also a new section on bottom navigation—making it easy to explore and switch between top-level views in a single tap.