docs: update readme with REPL desc

README.md

@@ -94,7 +94,20 @@ There are 3 ways in which data can be sent and received from at server.
     print(response)
 
     ```
-
+
+
+### CLI Tools
+* **REPL** - you can use this to type atPlatform commands and see responses; but the best thing about the REPL currently is that it shows the data notifications as they are received. The REPL code has the essentials of what a 'receiving' client needs to do - i.e.
+	* create an AtClient (assigning a Queue object to its queue parameter)
+	* start two new threads
+        * one for the AtClient.start_monitor() task: receives data update/delete notification events (the event data contains the ciphertext)
+        * the other one calls handle_event() method, which will read the upcoming events in the queue and handle them: 
+			* calling AtClient.handle_event() (to decrypt the notifications and introducing the result as a new event in the queue) 
+			* reading the new event, which contains the decrypted result 
+	* Instructions to run the REPL:
+		1) Run repl.py and choose an atSign using option `1`
+		2) Select option `2`. REPL will start and activate monitor mode automatically in a different thread. You can still send commands/verbs. You will start seeing your own notifications (from yourself to yourself) and heartbeat working (noop verb is sent from time to time as a keepalive)
+		3) Use `at_talk` or any other tool to send notifications to your atSign from a different atSign. You should be able to see the complete notification, and the encrypted and decrypted value of it.
 
 ## Open source usage and contributions