Add picked step to customer shipment workflow

issue9634
review329071002

tests/scenario_account_stock_continental.rst

@@ -201,6 +201,9 @@ Send 5 products::
     True
     >>> shipment.state
     'assigned'
+    >>> shipment.click('pick')
+    >>> shipment.state
+    'picked'
     >>> shipment.click('pack')
     >>> shipment.state
     'packed'