MAINTAINERS: Add myself as a collaborator

Have been working and contributing regularly to Wi-Fi, please see [1].

[1] - https://github.com/zephyrproject-rtos/zephyr/pulls?q=is%3Apr+is%3Aclosed+wifi+author%3Akrish2718



Signed-off-by: Chaitanya Tata <Chaitanya.Tata@nordicsemi.no>