Allow source of README.md from bash

Allow a "source README.md" from bash to reset the proxy file

README.md

+#!/usr/bin/env bash
 # ncsa_pac_files
+#
+#On macOS, this can be easily loaded/reloaded with a script like this:
 
-On macOS, this can be easily loaded/reloaded with a script like this:
-```
-#!/usr/bin/env bash
 set -x  # echo on
 PROXY_FILE_URL="https://git.ncsa.illinois.edu/rundall/ncsa_pac_files/-/raw/master/ncsa_http_proxy.pac"
 networksetup -setautoproxystate Wi-Fi off
 networksetup -setautoproxyurl Wi-Fi "$PROXY_FILE_URL"
 networksetup -getautoproxyurl Wi-Fi
-```
+set +x  # echo off