ratelimit: Adding a reference to the pipelimit module in README

modules/ratelimit/README

@@ -131,6 +131,10 @@ Chapter 1. Admin Guide
    associated with its own queue and a number of queues are connected to a
    certain pipe (see the queue and pipe params).
 
+   Please also take a look at the "pipelimit" module, that implements the
+   pipe policy with database support. Note that it doesn't implement the
+   queues that exist in this module.
+
 2. Use Cases
 
    Limiting the rate messages are processed on a system directly

modules/ratelimit/doc/ratelimit_admin.xml

@@ -27,6 +27,11 @@
 		associated with its own queue and a number of queues are connected
 		to a certain pipe (see the queue and pipe params).
 	</para>
+	<para>
+		Please also take a look at the <quote>pipelimit</quote> module,
+		that implements the pipe policy with database support. Note that it 
+		doesn't implement the queues that exist in this module.
+	</para>
 	</section>
 	<section>
 	<title>Use Cases</title>