Deprecate fdc(4) and floppy utilities

Floppies have been obsolete for over a decade.  Add a deprecation note
now and plan to remove fdc(4) support in 16.

Reviewed by:	ziaee
Sponsored by:	The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D41549

share/man/man4/fdc.4

@@ -25,7 +25,7 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd October 10, 2023
+.Dd November 16, 2025
 .Dt FDC 4
 .Os
 .Sh NAME
@@ -47,6 +47,12 @@ In
 .Cd hint.fd.1.at="fdc0"
 .Cd hint.fd.1.drive="1"
 .Cd hint.fd.1.flags="0x0"
+.Sh DEPRECATION NOTICE
+The
+.Nm
+driver is deprecated and may not be present in
+.Fx 16.0
+and later.
 .Sh DESCRIPTION
 .Ss Device Usage
 This driver provides access to floppy disk drives.