Article Audit: NVDA + VoiceOver articles

Created by: scottaohara

In reviewing the NVDA and VoiceOver articles for #669 (closed), there are some updates I think would be good to create a level of consistency between the two, as well as to provide a template to follow for future articles for JAWS and mobile screen readers.

The NVDA article (2015) is largely good as is, but adding in additional links to more in-depth usage articles/resources would be good here.

The VoiceOver article (2013) could use a listing of common key commands, like the NVDA article, and also links to more in-depth usage articles/resources.