some modifications in workers doc

Author: adipasquale

docs/jobs.md

@@ -1,10 +1,8 @@
 # Jobs & Tasks
 
-A **Job** is an unit of work that can be added to a Queue. It will be later dequeued by a Worker.
+A **Task** is a Python class wrapping a unit of processing. A task may invoke other tasks, synchronously or asynchronously (by queuing them as proper jobs).
 
-A **Task** is a Python class wrapping your asynchronous code.
-
-Jobs have a main Task, that will be called when the Job starts. In this Job context, the main Task can then call sub-Tasks or any other Python code.
+A **Job** is an instance of the execution of a Task. It must link to a specific Task via it's path and it must have parameters. It must be queued in a Queue. A Worker then dequeues and executes it. The worker updates it with metadata about it's execution : status, traceback ...
 
 ## Job statuses
 

docs/workers.md

@@ -1,7 +1,15 @@
+## Worker
 
-## Worker statuses
+A worker is a unit of processing, that dequeues jobs and executes them.
 
-A Worker is always in one of these statuses:
+It is started with a list of queues to listen to, in a specific order.
+
+It can be started with concurrency options (multiple processes and / or multiple greenlets). We call this whole group a single 'worker' even though it is able to dequeue multiple jobs in parallel.
+
+
+## Statuses
+
+At any time, a worker is in one of these statuses:
 
 * `init`: General worker initialization
 * `wait`: Waiting for new jobs from Redis