Add vdevprops.7 to the Makefile

Adding vdevprops.7 to the Makefile ensures that it gets installed
properly on FreeBSD.

Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Reviewed-by: Allan Jude <allan@klarasystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Daniel Ebdrup Jensen <debdrup@FreeBSD.org>
Closes openzfs#14527

man/Makefile.am

@@ -15,6 +15,7 @@ dist_man_MANS = \
 	%D%/man4/zfs.4 \
 	\
 	%D%/man7/dracut.zfs.7 \
+	%D%/man7/vdevprops.7 \
 	%D%/man7/zfsconcepts.7 \
 	%D%/man7/zfsprops.7 \
 	%D%/man7/zpool-features.7 \