SEC-944: Minor updates to schema appendix

src/docbkx/appendix-db-schema.xml

@@ -62,6 +62,10 @@ create table group_members (
   <section>
     <title>Persistent Login (Remember-Me) Schema</title>
     <para>
+      This table is used to store data used by the more secure
+      <link xlink:href="#remember-me-persistent-token">persistent token</link> remember-me implementation.
+      If you are using <classname>JdbcTokenRepositoryImpl</classname> either directly or through the namespace,
+      then you will need this table.
 <programlisting xml:id="db-schema-remeber-me">
 create table persistent_logins (
   username varchar(64) not null, 
@@ -75,7 +79,7 @@ create table persistent_logins (
   <section>
     <title>ACL Schema</title>
     <para>
-      
+      The tables used by the Spring Security <link xlink:href="domain-acls">ACL</link> implementation.
 <programlisting xml:id="dbschema-acl"> 
 create table acl_sid (
   id bigint generated by default as identity(start with 100) not null primary key,