docs: add correlation IDs to examples

README.md

@@ -33,9 +33,11 @@ Comments are prefixed with `--`, they are not part of transmissions.
 
 ```telnet
 >
+> abcd -- correlation ID, any string
 >
 > NEW 1234 -- 1234 is recipient's key
 
+abcd
 
 IDS QuCLU4YxgS7wcPFA YB4CCATREHkaQcEh -- recipient and sender IDs for the queue
 ```
@@ -44,9 +46,11 @@ IDS QuCLU4YxgS7wcPFA YB4CCATREHkaQcEh -- recipient and sender IDs for the queue
 
 ```telnet
 > -- no signature (just press enter)
+> bcda -- correlation ID, any string
 > YB4CCATREHkaQcEh -- sender ID for the queue
 > SEND :key abcd
 
+bcda
 YB4CCATREHkaQcEh
 OK
 ```
@@ -55,9 +59,11 @@ OK
 
 ```telnet
 > 1234 -- recipient's "signature" - same as "key" in the demo
+> cdab
 > QuCLU4YxgS7wcPFA -- recipient ID
 > KEY abcd -- "key" provided by sender
 
+cdab
 QuCLU4YxgS7wcPFA
 OK
 ```
@@ -66,9 +72,11 @@ OK
 
 ```telnet
 > abcd -- sender's "signature" - same as "key" in the demo
+> dabc -- correlation ID
 > YB4CCATREHkaQcEh -- sender ID
 > SEND :hello
 
+dabc
 YB4CCATREHkaQcEh
 OK
 ```
@@ -77,13 +85,16 @@ OK
 
 ```telnet
 
+-- no correlation ID for messages delivered without client command
 QuCLU4YxgS7wcPFA
 MSG ECA3w3ID 2020-10-18T20:19:36.874Z 5
 hello
 > 1234
+> abcd
 > QuCLU4YxgS7wcPFA
 > ACK
 
+abcd
 QuCLU4YxgS7wcPFA
 OK
 ```