Simplify request configuration

Currently, end-user needs to provide a link to the shapefile and the geodfile in the .cfg request file.

Most of the time, the link would point to the default files provided as part or S1Tiling resources. As S1Tiling may be installed anywhere with pip, it's better to not have the end-user search where this anywhere actually is to provide the exact pathname.

Instead, when shapefile and geodfile options shall have a default value that automatically points to the relevant resource files distributed with S1Tiling.

• Provide default value to the resources/ files
• Update the documentation