[2.1.8] Inaccuracies in PlatfomBackdrop documentation

[Hanodest]

atmosphere_color has incorrect default. Screenshots for a planet with platform_backdrop = {}:

backdrop-default.png (165.21 KiB) Viewed 34 times

and with platform_backdrop = {atmosphere_color = { 0.095, 0.15, 0.19, 0.1 }}:

backdrop-explicit.png (227.5 KiB) Viewed 34 times

. The actual default seems to be { 0.095, 0.15, 0.19, 1.0 } (1.0 instead of 0.1 in alpha channel)

specular_color and light_color are not actually multiplied by 10 in the shader. Only atmosphere_* colors are.