Write a script that creates six sub-plots in two columns each with three rows. Each plot should have an appropriate title and labels on the x and y axes. The plot in the top left sub-plot should be y = cos(θ) for values of θ from -2π to 2π. Subsequent plots going across the rows before going down the columns should be of y = 2cos(θ), y = 3cos(θ), etc., to y = 6cos(θ) over the same range of θ.