Slow Cooker Lemon Chicken Artichoke Soup

– 1 1/2 lbs. bone-in skinless chicken breasts

leeks, white and light green parts only, cleaned, halved, and sliced into half moons

stalk celery, halved and chopped

garlic, minced

(1) bay leaf

(1) 14 ounce can artichoke hearts packed in water, drained, or frozen artichoke hearts

low sodium chicken stock

water (or you may use more chicken stock)

bunch kale, torn (discard the tough stems)*

Additional salt and freshly ground black pepper,

Juice of 1 large lemon