Update categories.txt
Update categories.txt

Added "Two-crust Pies, 2 crust pies" as a sub-category of "Pies"
openfoodfacts/openfoodfacts-server,openfoodfacts/openfoodfacts-server,openfoodfacts/openfoodfacts-server,openfoodfacts/openfoodfacts-server,openfoodfacts/openfoodfacts-server