Please add ability to add R^2 value and equation to geom_smooth(), like in excel

[stasb80-arch]

Please add ability to add R^2 value and equation to geom_smooth(), like in excel.
That might be simple for some people to implement, but once you have the ability to add that, in code, via a few function or flags, that would save me a lot of time, and will be very convenient

[alshan]

I like it.