Breast milk is better for babies than cow's milk. There is a nutritional shift in human milk that happens soon if your child is about to turn 1, but it does not mean cow's milk is better for a human baby, it is not.
Pediatricians recommend you breastfeed untill baby is AT LEAST 2 and then continue from then untill you feel it's time to stop. While there's nothing wrong at all with stopping at one if that's what you want to do, but that is 100% not true. While your baby will need more and more of other foods, Breastmilk is made exactly for your baby to the point that the content of your Breastmilk will change as baby gets older to be tailored to exactly what your baby needs are for each age. Your Breastmilk even goes so far as to produces antibodies for any viruses or bugs it detects in your babies saliva to build babies immune system and fight illnesses. It's truly is an amazing thing. No cows milk could ever compare. Your pediatrician may want you to give your baby vitamin D supplaments because they're not drinking vitamin D enriched milk, but that's something you would talk to the pediatrician about. In the end though that's not true, Breastmilk is still a fantastic source of nutrients for your baby and you should stop whenever you feel you want to.