#360 barumerli2023_featureextraction downloads default grid if no specific one is specified

[Katharina Pollack]

In the documentation it says under additional input parameters:

"'dirs' Specify custom spatial grid for templates provided as a barumerli2023_coordinates class."

Please clarify that if no grid is specified, a default grid will be downloaded (only from version amt-1.3.0).

[Roberto Barumerli]

done