Fix example usage for nested objects

[thschmitt]

Currently, the example shows an unnecessary object assigment for nested parameters, e.g.

--instances object (multiple)

   Example:
     config=object; config.memory=float; config.cpu=float;

With this fix, the config=object; assigment will no be shown anymore:

--instances object (multiple)

   Example:
     config.memory=float; config.cpu=float;