Update link to Zephyr docs.

README.md

@@ -269,7 +269,7 @@ The following extensions can be added into MakeCode by copying the GitHub URL an
 - [ChibiOS](https://github.com/ChibiOS/ChibiOS-Contrib) - A complete development environment for embedded applications including RTOS, a HAL, peripheral drivers, support files, and tools.
 - [Mynewt](https://github.com/apache/mynewt-core) - Open-source operating system for tiny embedded devices. Its goal is to make it easy to develop applications for microcontroller environments where power and cost are driving factors.
 - [RIOT](https://doc.riot-os.org/group__boards__microbit.html) - A friendly, real-time, multi-threading operating system that supports a range of devices that are typically found in the Internet of Things (IoT).
-- [Zephyr](https://docs.zephyrproject.org/latest/boards/arm/bbc_microbit/doc/index.html) - A scalable real-time operating system (RTOS) supporting multiple hardware architectures, optimized for resource constrained devices, and built with security in mind.
+- [Zephyr](https://docs.zephyrproject.org/latest/boards/bbc/microbit_v2/doc/index.html) - A scalable real-time operating system (RTOS) supporting multiple hardware architectures, optimized for resource constrained devices, and built with security in mind.
 
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