add simple start script

start.sh

+#!/bin/sh
+
+set -euo pipefail
+
+BINARY="target/release/cats-sdr-igate"
+
+cargo build --release
+
+rtl_fm -M raw -F9 -p 0 -d 0 -s 48000 -f 430500000 - 2>/dev/null | $BINARY