[DATFromDir] Fix filename as filename and update description flag in help

SabreTools.Helper/Data/Build.cs

@@ -92,7 +92,7 @@ Options:
 	-ro, --romba		Read files from a Romba input
 	-f=, --filename=	Set the external name of the DAT
 	-n=, --name=		Set the internal name of the DAT
-	-d=, --desc=		Set the description of the DAT
+	-de=, --desc=		Set the description of the DAT
 	-c=, --cat=		Set the category of the DAT
 	-v=, --version=		Set the version of the DAT
 	-au=, --author=		Set the author of the DAT

SabreTools/Partials/SabreTools_Inits.cs

@@ -400,7 +400,7 @@ namespace SabreTools
 			// Create a new DATFromDir object and process the inputs
 			Dat datdata = new Dat
 			{
-				FileName = description,
+				FileName = filename,
 				Name = name,
 				Description = description,
 				Category = category,