Unify doc-strings (remove type/rtype)

As this information is already provided in type hints and we don't need to maintain it in two places.

src/ifcopenshell-python/ifcopenshell/api/cost/add_cost_item.py

@@ -38,13 +38,10 @@ def add_cost_item(
     :param cost_schedule: If the cost item is to be added as a root or top
         level cost item to a cost schedule, the IfcCostSchedule may be
         specified. This is mutually exlclusive to the cost_item parameter.
-    :type cost_schedule: ifcopenshell.entity_instance, optional.
     :param cost_item: If the cost item is to be added as a subitem to an
         existing cost item, the parent IfcCostItem may be specified. This is
         mutually exclusive to the cost_schedule parameter.
-    :type cost_item: ifcopenshell.entity_instance, optional
     :return: The newly created IfcCostItem
-    :rtype: ifcopenshell.entity_instance
 
     Example:
 

src/ifcopenshell-python/ifcopenshell/api/cost/calculate_cost_item_resource_value.py

@@ -40,9 +40,7 @@ def calculate_cost_item_resource_value(file: ifcopenshell.file, cost_item: ifcop
     previously existing values are removed.
 
     :param cost_item: The IfcCostItem to calculate
-    :type cost_item: ifccopenshell.entity_instance.entity_instance
     :return: None
-    :rtype: None
 
     Example:
 

src/ifcopenshell-python/ifcopenshell/api/cost/edit_cost_value_formula.py

@@ -34,11 +34,8 @@ def edit_cost_value_formula(file: ifcopenshell.file, cost_value: ifcopenshell.en
     For more information, see ifcopenshell.util.cost
 
     :param cost_value: The IfcCostValue to set the values of
-    :type cost_value: ifcopenshell.entity_instance
     :param formula: The formula following the language of ifcopenshell.util.cost
-    :type formula: str
     :return: None
-    :rtype: None
 
     Example:
 

src/ifcopenshell-python/ifcopenshell/api/cost/remove_cost_schedule.py

@@ -28,9 +28,7 @@ def remove_cost_schedule(file: ifcopenshell.file, cost_schedule: ifcopenshell.en
     including all cost items.
 
     :param cost_schedule: The IfcCostSchedule entity you want to remove
-    :type cost_schedule: ifcopenshell.entity_instance
     :return: None
-    :rtype: None
 
     Example: