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/group/remove_group.py

@@ -28,9 +28,7 @@ def remove_group(file: ifcopenshell.file, group: ifcopenshell.entity_instance) -
     the group will be removed.
 
     :param group: The IfcGroup entity you want to remove
-    :type group: ifcopenshell.entity_instance
     :return: None
-    :rtype: None
 
     Example:
 

src/ifcopenshell-python/ifcopenshell/api/group/unassign_group.py

@@ -29,11 +29,8 @@ def unassign_group(
     If the product isn't assigned to the group, nothing will happen.
 
     :param products: A list of IfcProduct elements to unassign from the group
-    :type products: list[ifcopenshell.entity_instance]
     :param group: The IfcGroup to unassign from
-    :type group: ifcopenshell.entity_instance
     :return: None
-    :rtype: None
 
     Example:
 

src/ifcopenshell-python/ifcopenshell/api/group/update_group_products.py

@@ -31,11 +31,8 @@ def update_group_products(
     removed.
 
     :param products: A list of IfcProduct elements to assign to the group
-    :type products: list[ifcopenshell.entity_instance]
     :param group: The IfcGroup to assign the products to
-    :type group: ifcopenshell.entity_instance
     :return: The IfcRelAssignsToGroup relationship
-    :rtype: ifcopenshell.entity_instance
 
     Example: