correct table name and add some information about global address book

config/conf.pl

@@ -2766,7 +2766,8 @@ sub command98 {
 
 sub command99 {
     print "This is the name of the table you want to store the global address book\n";
-    print "data in, it defaults to 'global_address'\n";
+    print "data in. Default table name is 'global_abook'. Address book uses same\n";
+    print "database format as personal address book.\n";
     print "\n";
     print "[$WHT$addrbook_global_table$NRM]: $WHT";
     $new_table = <STDIN>;

doc/db-backend.txt

@@ -79,7 +79,9 @@ administration plugin. The DSN should look something like:
 From now on all users' personal addressbooks will be stored in a
 database.
 
-
+Global address book uses same table format as the one used for personal
+address book. You can even use same table, if you don't have user named
+'global'.
 
 Configuring preferences in database
 -----------------------------------