hier.7: add /lib/casper directory

Reported by:	imp
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation

share/man/man7/hier.7

@@ -28,7 +28,7 @@
 .\"	@(#)hier.7	8.1 (Berkeley) 6/5/93
 .\" $FreeBSD$
 .\"
-.Dd June 18, 2018
+.Dd December 6, 2018
 .Dt HIER 7
 .Os
 .Sh NAME
@@ -144,6 +144,10 @@ and
 .Pa /sbin
 .Pp
 .Bl -tag -width "defaults/" -compact
+.It Pa casper/
+service-specific
+.Xr libcasper 3
+Capsicum support libraries
 .It Pa geom/
 class-specific libraries for the
 .Xr geom 8