Cross-reference libbe(3) and bectl(8).

Those two manual pages are already referencing each other in the HISTORY
sections, which people might skip. Mention those manual pages explicitly in
the SEE ALSO sections.  Also, remove a reference to be(1) from libbe(3).

Reviewed by:	bcr
Approved by:	krion (mentor, implicit), mat (mentor, implicit)
Differential Revision:	https://reviews.freebsd.org/D18136

lib/libbe/libbe.3

@@ -484,7 +484,7 @@ BE_ERR_NOMEM
 BE_ERR_UNKNOWN
 .El
 .Sh SEE ALSO
-.Xr be 1
+.Xr bectl 8
 .Sh HISTORY
 .Nm
 and its corresponding command,

sbin/bectl/bectl.8

@@ -18,7 +18,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd August 24, 2018
+.Dd November 21, 2018
 .Dt BECTL 8
 .Os
 .Sh NAME
@@ -263,6 +263,7 @@ will force the unmount if busy.
 To fill in with jail upgrade example when behavior is firm.
 .El
 .Sh SEE ALSO
+.Xr libbe 3 ,
 .Xr jail 8 ,
 .Xr zfs 8 ,
 .Xr zpool 8