sort: document -b

sort.1

@@ -3,7 +3,7 @@
 sort \- sort lines
 .SH SYNOPSIS
 .B sort
-.RB [ \-nru ]
+.RB [ \-bnru ]
 .RB [ \-k
 .I key
 .R ]...
@@ -14,6 +14,9 @@ writes the sorted concatenation of the given files to stdout.  If no file is
 given, sort reads from stdin.
 .SH OPTIONS
 .TP
+.B \-b
+skip leading whitespace of columns when sorting.
+.TP
 .B \-n
 perform a numeric sort.
 .TP

sort.c

@@ -41,7 +41,7 @@ static bool bflag = false;
 static void
 usage(void)
 {
-	enprintf(2, "usage: %s [-nru] [-k def]... [file...]\n", argv0);
+	enprintf(2, "usage: %s [-bnru] [-k def]... [file...]\n", argv0);
 }
 
 int