Documentation: Chart of features in different version

[willwade]

In doing the iOS deprecation issues recently (and looking to fund a round of further dev) - I'm trying to figure out whats missing between the windows (5b) version and the iOS version. A user could do with a chart documenting the various features and functions in the different versions.

(I've made a dummy table what I'm thinking here: http://dasher-site.netlify.com/en/get-started/)