Prop

align Type: String | Values: left | center | right (defaults to center)
verticalAlign Type: String | Values: top | middle | bottom (defaults to bottom)
layout Type: String | Values: horizontal | vertical | proximate (defaults to horizontal)
x Type: Number (defaults to 0)
y Type: Number (defaults to 0)

layout determines the position of the legend items
layout: proximate will place the legend items as close as possible to the graphs they’re representing. It will also determine whether to place the legend above/below or on the side of the plot area, if the legend is in a corner.

x offsets the legend relative to its horizontal alignment. Negative x moves it to the left, positive x moves it to the right

y offsets the legend relative to its vertical alignment. Negative y moves it up, positive y moves it down.