[Docs] Fix usage of article "an" before a consonant sound (#51803)
Because `<Carousel />` starts with the consonant, "C", the preceding article should be "a" not "an".
Reference: [https://www.merriam-webster.com/words-at-play/is-it-a-or-an](https://www.merriam-webster.com/words-at-play/is-it-a-or-an)