Add platform documentation for the Realtek RTL8721F: a chip overview
page and the rtl8721f_evb board page, modelled on the existing RTL8720F
/ RTL8721Dx docs. The platform index picks them up automatically via
its */index glob.
The pages cover the vendor-SDK/toolchain dependency, the make and CMake
build/flash flow, and the hardware-verified features: NSH over the
LOG-UART console, littlefs at /data on the on-chip NOR flash, Wi-Fi
station and SoftAP via the wapi tool, and the DHCP client/server.
Signed-off-by: dechao_gong <dechao_gong@realsil.com.cn>
Co-Authored-By: Claude <noreply@anthropic.com>