We use a custom sphinx EnvironmentCollector to make the toctree more interactible. For that reason we also implemented our own way of changing the depth level of the toctree.
In order to change the toctree depth level locate the conf.py file and change / add the depth variable. For now only depth=2 and depth=3 make sense, since by default the toctree extends to 2 level and does not exceed 3.