p9fs.4: MLINK to virtio_p9fs.4

Technically, virtio_p9fs is an emulated device that masquerades
as a p9fs mount, but it does not make sense to have two separate manual
pages.

Reviewed by:	bnovkov, dfr
MFC after:	3 days
Differential Revision:	https://reviews.freebsd.org/D57013

share/man/man4/Makefile

@@ -784,6 +784,7 @@ MLINKS+=${_nfe.4} ${_if_nfe.4}
 MLINKS+=nge.4 if_nge.4
 MLINKS+=openfirm.4 openfirmware.4
 MLINKS+=ow.4 onewire.4
+MLINKS+=p9fs.4 virtio_p9fs.4
 MLINKS+=pccbb.4 cbb.4
 MLINKS+=pcm.4 snd.4 \
 	pcm.4 sound.4

share/man/man4/p9fs.4

@@ -22,11 +22,12 @@
 .\" (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 May 15, 2026
+.Dd May 18, 2026
 .Dt P9FS 4
 .Os
 .Sh NAME
-.Nm p9fs
+.Nm p9fs ,
+.Nm virtio_p9fs
 .Nd "9P file system"
 .Sh SYNOPSIS
 To use this filesystem,