boards: link_board_eth: Update outdated link
boards: link_board_eth: Update outdated link

This commit updates the outdated link for "link board ETH Website" with
that of the "reel board," which contains the information on the "link
board ETH."

Signed-off-by: Stephanos Ioannidis <d862a8ba07ce1656f326514118a4618b42d2d2c0@nordicsemi.no>

finikorg/zephyr,galak/zephyr,galak/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,galak/zephyr,finikorg/zephyr