Shows the food and saturation for any edible item on the tooltip. Should work with all food, whether it is from another mod or not.
For example, Rabbit Stew is "10 (0.6)"
EDIT: I found the post that inspired this mod https://www.reddit.com/r/minecraftsuggestions/comments/3brh7v/when_hovering_over_a_food_it_shows_how_many_food/