justforfunc #34: Plotting Data with gonum/plot (ML4G #1)

For the first episode of this mini series on Machine Learning for Gophers (#ML4G) we're going to learn how to plot data with gonum/plot.

It might seem simple, but there's lots to learn!

References:
- gonum: https://gonum.org
- gonum/plot docs: https://godoc.org/gonum.org/v1/plot
- source code: https://github.com/campoy/justforfunc/tree/master/34-gonum-plot