Correct -q's arg name in rgbgfx(1) (#1826)

Author: ReiquelApplegate

man/rgbgfx.1

@@ -347,7 +347,7 @@ Output the image's palette set to this file.
 Same as
 .Fl p Ar base_path Ns .pal
 .Pq see Sx Automatic output paths .
-.It Fl q Ar pal_file , Fl \-palette-map Ar pal_file
+.It Fl q Ar pal_map , Fl \-palette-map Ar pal_map
 Output the image's palette map to this file.
 This is useful if the input image contains more than 8 palettes, as the attribute map only contains the lower 3 bits of the palette indices.
 .It Fl Q , Fl \-auto-palette-map