More expansive UX writing/style guide

[danirabbit]

There's a lot of things we've done over the years to create the voice for elementary, I wonder if it would make sense to include a style guide as part of the HIG under like a whole UX writing section.

It would be good at least to have some kind of documentation about avoiding overusing words like "simple" and "powerful", or the word "just", or leaning towards "people" instead of "users". There's a lot of little word choice things we should document in some way