od: document skip (-j) option

od.1

@@ -8,6 +8,7 @@
 .Nm
 .Op Fl A Ar addrformat
 .Op Fl E | e
+.Op Fl j Ar skip
 .Op Fl t Ar outputformat...
 .Op Fl v
 .Op Ar file ...
@@ -33,6 +34,10 @@ Force Little Endian
 or Big Endian
 .Fl ( E )
 system-independently.
+.It Fl j Ar skip
+Ignore the first
+.Ar skip
+bytes of input.
 .It Fl t Ar outputformat
 .Ar outputformat
 is a list of a|c|d|o|u|x followed by a digit or C|S|I|L and sets

od.c

@@ -176,8 +176,8 @@ lcm(unsigned int a, unsigned int b)
 static void
 usage(void)
 {
-	eprintf("usage: %s [-A addressformat] [-E | -e] [-t outputformat] "
-	        "[-v] [file ...]\n", argv0);
+	eprintf("usage: %s [-A addressformat] [-E | -e] [-j skip] "
+	        "[-t outputformat] [-v] [file ...]\n", argv0);
 }
 
 int