Correct typo in ERRORS, and document that getdents(2) can return

directory entries that refer to deleted files, all per PR 10567.

lib/libc/sys/getdents.2

@@ -1,4 +1,4 @@
-.\"	$NetBSD: getdents.2,v 1.6 2000/11/21 23:35:10 wiz Exp $
+.\"	$NetBSD: getdents.2,v 1.7 2001/03/16 07:58:24 fair Exp $
 .\"
 .\" Copyright (c) 1989, 1991, 1993
 .\"	The Regents of the University of California.  All rights reserved.
@@ -83,12 +83,18 @@ Files that are linked by hard links (see
 .Xr link 2 )
 have the same
 .Fa d_fileno .
+If
+.Fa d_fileno
+is zero, the entry refers to a deleted file.
+.Pp
 The
 .Fa d_reclen
 entry is the length, in bytes, of the directory record.
+.Pp
 The
 .Fa d_name
 entry contains a null terminated file name.
+.Pp
 The
 .Fa d_namlen
 entry specifies the length of the file name excluding the null byte.
@@ -125,7 +131,7 @@ Otherwise, -1 is returned and the global variable
 .Va errno
 is set to indicate the error.
 .Sh ERRORS
-.Fn gtdents
+.Fn getdents
 will fail if:
 .Bl -tag -width Er
 .It Bq Er EBADF