Delete old guide (What makes a good routing node)

[Liongrass]

This old guide hasn't been surfaced for a long while, but seems to still be present in the repo. Links in this article lead to nowhere which is causing issue #670

Pull Request Checklist

• [ V] The documents updated are not in the docs/ directory. These files are synced from upstream repositories (lnd, lit, loop, pool and faraday), and should be updated in their parent repo.