Change backend reference from slapd-bdb to slapd-mdb

doc/man/man5/slapo-unique.5

@@ -8,7 +8,7 @@ slapo\-unique \- Attribute Uniqueness overlay to slapd
 ETCDIR/slapd.conf
 .SH DESCRIPTION
 The Attribute Uniqueness overlay can be used with a backend database such as
-.BR slapd\-bdb (5)
+.BR slapd\-mdb (5)
 to enforce the uniqueness of some or all attributes within a
 scope. This subtree defaults to all objects within the subtree of the
 database for which the Uniqueness overlay is configured.