documentation: add description of the session identification

Follows up #85

Author: LeonidVas

README.md

@@ -26,6 +26,7 @@ align="right">
   * [Initialization](#initialization)
   * [Creating a new queue](#creating-a-new-queue)
   * [Set queue settings](#set-queue-settings)
+  * [Session identification](#session-identification)
   * [Putting a task in a queue](#putting-a-task-in-a-queue)
   * [Taking a task from the queue ("consuming")](#taking-a-task-from-the-queue-consuming)
   * [Acknowledging the completion of a task](#acknowledging-the-completion-of-a-task)
@@ -372,6 +373,20 @@ Available `options`:
 `ttr` - time to release in seconds. The time after which, if there is no active
 connection in the session, it will be released with all its tasks.
 
+## Session identify
+
+```lua
+queue.identify(session_uuid)
+```
+In the queue the session has a unique UUID and one session can have many
+connections. Also, the consumer can reconnect to the existing session during the
+ `ttr` time.  
+To get the UUID of the current session, call the `queue.identify()`
+without parameters.  
+To connect to the existing session, call the `queue.identify(session_uuid)`
+with the UUID of the session.  
+In case of failure, an error will be thrown.
+
 ## Putting a task in a queue
 
 To insert a new task into a queue, use: