Add comment about compression

dbclient.1

@@ -20,6 +20,9 @@ dbclient \- lightweight SSH client
 .SH DESCRIPTION
 .B dbclient
 is a small SSH client 
+.P
+If compiled with zlib support and if the server supports it, dbclient will
+always use compression.
 .SH OPTIONS
 .TP
 .B \-p \fIport