【Requirement Value】：
In order to increase the usage scenarios of OpenHarmony, more Hardware support are needed.
For oversea market(mainly EU), OpenHarmony Eclipse Project team suggests to add support for more dev boards.

【Requirement Description】：
Add nRF52840 DK dev board support

Dependency of the hardware support:

• Bitbake, Zephyr

【Useful Links】：

1. Detailed specifications of nRF52840 DK
2. OpenHarmony ECLIPSE Project - nRF52840 DK dev board support
3. Hardware list already supported in OpenHarmony Eclipse Project, including physical boards & virtual targets