Add overlay to rgblink manpage
.Op Fl t
.Op Fl m Ar mapfile
.Op Fl n Ar symfile
+.Op Fl O Ar overlayfile
.Op Fl o Ar outfile
.Op Fl p Ar pad_value
.Op Fl s Ar symbol
@@ -32,6 +33,10 @@ The arguments are as follows:
Write a mapfile to the given filename.
.It Fl n Ar symfile
Write a symbol file to the given filename.
+.It Fl O Ar overlayfile
+The ROM image to overlay sections over.
+When an overlay ROM is provided, all sections must be fixed.
+This may be used to patch an existing binray.
.It Fl o Ar outfile
Write ROM image to the given filename.
.It Fl p Ar pad_value
