Reinstate subordinate directive, delete references to slapo-glue

doc/man/man8/slapadd.8

@@ -26,9 +26,9 @@ database.
 It opens the given database determined by the database number or
 suffix and adds entries corresponding to the provided LDIF to
 the database.
-Subordinate databases glued with
-.BR slapo-glue (5)
-are also updated.
+Databases configured as
+.B subordinate
+of this one are also updated.
 The LDIF input is read from standard input or the specified file.
 .LP
 As

doc/man/man8/slapcat.8

@@ -27,9 +27,9 @@ database.
 It opens the given database determined by the database number or
 suffix and writes the corresponding LDIF to standard output or
 the specified file.
-Subordinate databases glued with
-.BR slapo-glue (5)
-are also output.
+Databases configured as
+.B subordinate
+of this one are also output.
 .LP
 The LDIF generated by this tool is suitable for use with
 .BR slapadd (8).

doc/man/man8/slapindex.8

@@ -24,9 +24,9 @@ indices based upon the current contents of a database.
 It opens the given database determined by the database number or
 suffix and updates the indices for all values of all attributes
 of all entries.
-Subordinate databases glued with
-.BR slapo-glue (5)
-are also re-indexed.
+Databases configured as
+.B subordinate
+of this one are also re-indexed.
 .SH OPTIONS
 .TP
 .B \-v