update docstring

Signed-off-by: Thijs Baaijen <13253091+Thijss@users.noreply.github.com>

Author: Thijss

src/power_grid_model_ds/_core/model/arrays/base/array.py

@@ -52,6 +52,7 @@ class FancyArray(ABC):  # noqa: B024
     Note on string-columns:
         The default length for string columns is stored in _DEFAULT_STR_LENGTH.
         To change this, you can set the _str_lengths class attribute.
+        The _str_lengths attribute is inherited by child classes.
 
     Example:
         >>> class MyArray(FancyArray):