Clarified readme a bit

README.md

@@ -26,25 +26,30 @@ When those files do not exist, they are skipped (i.e. this is not an error). The
 should be in INI format, as specified by the
 [configparser documentation](https://docs.python.org/3/library/configparser.html)
 
+
 ### Configuration contents:
 
 All configuration keys should be placed in the `[flamenco-worker]` section of the
 config files.
 
 - `manager_url`: Flamenco Manager URL.
-- `worker_id`: ID of the worker, handed out by the Manager upon registration (see
-  Registration below) and used for authentication with the Manager.
-- `worker_secret`: Secret key of the worker, given to the Manager upon registration
-  and authentication.
 - `job_types`: Space-separated list of job types this worker may execute.
 - `task_update_queue_db`: filename of the SQLite3 database holding the queue of task
   updates to be sent to the Master.
+These configuration keys are also required, but are created automatically upon startup
+when they don't exist yet:
+
+- `worker_id`: ID of the worker, handed out by the Manager upon registration (see
+  Registration below) and used for authentication with the Manager.
+- `worker_secret`: Secret key of the worker, generated by the Worker and given to the
+  Manager upon registration and authentication.
+
 
 ### TODO
 
 - Certain settings are currently only settable by editing constants in the Python source code.
   It might be nice to read them from the config file too, at some point.
-- Update worker address in MongoDB when communicating with it.
+
 
 ## Invocation