The first parameter (template name) is required, while the second (alternate tag page) is not.

This template is placed on a category page to inform editors of how to add files to that category using a template.

Example

{{Image template notice|PD-art|free=yes}} returns:

To place a file in this category, add the tag {{PD-art}} to the bottom of the file's description page. If you are not sure which category a file belongs to, consult the file copyright tag page. If this category is very large, please consider placing your file in a new or existing subcategory. Free files can be moved to the Wikimedia Commons.

The |free=yes parameter prevents the template from including the __NOGALLERY__ behavior switch in the category. See WP:NFG for more info.