You may change the image name as you like.

docker build --rm -t linkit-smart .

Notice for the menuconfig step, please select the following options to set target profile per below:

• Target System: Ralink RT288x/RT3xxx
• Subtarget: MT7688 based boards
• Target Profile: LinkIt 7688

docker run -it linkit-smart /bin/bash
cd /openwrt
./scripts/feeds update && ./scripts/feeds install -a
make menuconfig
make V=99

The resulting bootloader file is uboot.bin

docker run -it linkit-smart /bin/bash
cd /linkit-smart-uboot
make