Recommend global-agent

[gajus]

Hello @koichik ,

Thank you for maintaining tunnel. I have been using it the past couple of months. However, I've started running into issues with Node v12. I tried digging into tunnel/ gobal-tunnel-ng codebase, but found that all the patches for legacy Node.js versions made it hard to comprehend the database. I have since written a HTTP/HTTPS agent for Node.js v12 and above – https://github.com/gajus/global-agent. Would you like to become a contributor?

Equally if you find global-agent a useful alternative to tunnel for new Node.js versions, I would appreciate if you mention it in README.md.

Thank you