bathy_plane_calc: Add a clarifying message
bathy_plane_calc: Add a clarifying message

NeoGeographyToolkit/StereoPipeline,oleg-alexandrov/StereoPipeline,oleg-alexandrov/StereoPipeline,NeoGeographyToolkit/StereoPipeline,NeoGeographyToolkit/StereoPipeline,NeoGeographyToolkit/StereoPipeline,NeoGeographyToolkit/StereoPipeline,oleg-alexandrov/StereoPipeline,NeoGeographyToolkit/StereoPipeline,oleg-alexandrov/StereoPipeline,oleg-alexandrov/StereoPipeline,oleg-alexandrov/StereoPipeline