Update serve to account for live-reload

[drse]

#!/bin/bash

PORT=4005
LRPORT=35729

docker run -it --init --rm -v `pwd`:/docs:z -p $PORT:$PORT -p $LRPORT:$LRPORT drse/bookflow --port $PORT --lrport $LRPORT serve . ./build/_book

Note: live-reload plugin currently does not support a custom port, 35729 by default.