Update arg_desc.jl (#2830)

Mention aspect_ratio = :none

src/arg_desc.jl

@@ -110,7 +110,7 @@ const _arg_desc = KW(
 :legendtitlefont          => "Font. Font of the legend title.",
 :annotations              => "(x,y,text) tuple(s).  Can be a single tuple or a list of them.  Text can be String or PlotText (created with `text(args...)`)  Add one-off text annotations at the x,y coordinates.",
 :projection               => "Symbol or String.  '3d' or 'polar'",
-:aspect_ratio             => "Symbol (:equal) or Number. Plot area is resized so that 1 y-unit is the same size as `aspect_ratio` x-units.",
+:aspect_ratio             => "Symbol (:equal or :none) or Number. Plot area is resized so that 1 y-unit is the same size as `aspect_ratio` x-units. With `:none`, images inherit aspect ratio of the plot area.",
 :margin                   => "Measure (multiply by `mm`, `px`, etc). Base for individual margins... not directly used.  Specifies the extra padding around subplots.",
 :left_margin              => "Measure (multiply by `mm`, `px`, etc) or `:match` (matches `:margin`).  Specifies the extra padding to the left of the subplot.",
 :top_margin               => "Measure (multiply by `mm`, `px`, etc) or `:match` (matches `:margin`).  Specifies the extra padding on the top of the subplot.",