[skip ci] document first appearance of fhlink et al

MFC after:	1 week
Sponsored by:	Axcient
Reviewed by:	imp
Differential Revision: https://reviews.freebsd.org/D37575

lib/libc/sys/fhlink.2

@@ -25,7 +25,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd February 23, 2021
+.Dd November 30, 2022
 .Dt FHLINK 2
 .Os
 .Sh NAME
@@ -248,3 +248,10 @@ nor a file descriptor associated with a directory.
 .Xr fhopen 2 ,
 .Xr fhreadlink 2 ,
 .Xr fhstat 2
+.Sh HISTORY
+The
+.Fn fhlink
+and
+.Fn fhlinkat
+system calls first appeared in
+.Fx 12.1 .

lib/libc/sys/fhreadlink.2

@@ -25,7 +25,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd March 30, 2020
+.Dd November 30, 2022
 .Dt FHREADLINK 2
 .Os
 .Sh NAME
@@ -92,3 +92,8 @@ is no longer valid
 .Sh SEE ALSO
 .Xr fhstat 2 ,
 .Xr fhlink 2 ,
+.Sh HISTORY
+The
+.Fn fhreadlink
+system call first appeared in
+.Fx 12.1 .

lib/libc/sys/getfh.2

@@ -29,7 +29,7 @@
 .\"	@(#)getfh.2	8.1 (Berkeley) 6/9/93
 .\" $FreeBSD$
 .\"
-.Dd December 23, 2021
+.Dd November 30, 2022
 .Dt GETFH 2
 .Os
 .Sh NAME
@@ -224,3 +224,11 @@ The
 .Fn getfh
 system call first appeared in
 .Bx 4.4 .
+The
+.Fn lgetfh
+system call first appeared in
+.Fx 5.3 .
+The
+.Fn getfhat
+system call first appeared in
+.Fx 12.1 .