Create a dedicated document covering how to "Create and style text"

[parlough]

Core to many app experiences is text, but we kind of gloss over it, assuming it's well understood. We need a doc which goes over creating text and what you can do with it:

• Creating text
• Styling text
• Laying out text (wrap, overflow, etc)
• Combining text
• Making text selectable

This doc should likely go under Design & theming > Text.