zcbor missing in the list of implementations

[hubertmis]

Zephyr RTOS maintains and uses a zcbor C library: https://github.com/zephyrproject-rtos/zcbor. The project switched to this implementation from TinyCBOR in 2021: zephyrproject-rtos/zephyr#40591

zcbor could be added to the list of the cbor implementations.