correct history, dirfd() did not appear until tahoe

lib/libc/gen/opendir.3

@@ -1,4 +1,4 @@
-.\"	$OpenBSD: opendir.3,v 1.3 2024/03/23 16:30:01 guenther Exp $
+.\"	$OpenBSD: opendir.3,v 1.4 2026/05/01 11:25:21 jsg Exp $
 .\"
 .\" Copyright (c) 1983, 1991, 1993
 .\"	The Regents of the University of California.  All rights reserved.
@@ -27,7 +27,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd $Mdocdate: March 23 2024 $
+.Dd $Mdocdate: May 1 2026 $
 .Dt OPENDIR 3
 .Os
 .Sh NAME
@@ -297,12 +297,15 @@ The
 .Fn telldir ,
 .Fn seekdir ,
 .Fn rewinddir ,
-.Fn closedir ,
 and
-.Fn dirfd
+.Fn closedir
 functions appeared in
 .Bx 4.2 .
 The
+.Fn dirfd
+function appeared in
+.Bx 4.3 Tahoe .
+The
 .Fn fdopendir
 function appeared in
 .Ox 5.0 .