clarify template use of .Value

anydb.pod

@@ -452,6 +452,14 @@ The following template variables can be used:
 
 =item B<.Value> - string
 
+To be  able to use  the value  in a template,  you'll need to  add the
+C<-s>   flag   so   that   values  are   included   in   output   data
+stream. Otherwise you can only use `.Preview`.
+
+=item B<.Preview> string
+
+First line of entry value (if it is a string).
+
 =item B<.Bin> - []byte
 
 =item B<.Created> - timestamp.Time