Ahodges/doc/doc1117

@mulby , @shnayder , @WatsonEmily , @mhoeber , @catong , @srpearce , @stroilova , @dsjen please review. I do not yet have images to illustrate my examples, but otherwise ready.
well, it's actually meant to mimic the three UI labels that you use to navigate to the chart in question (this is the "alt" and I don't actually know whether a capitalized word within the alt is treated any differently by a screen reader)
So, I asked Mark S and the answer is that "a screen reader will annunciate a camelcased word just like it would space separated words"