Open GitHub Discussion listing of repo

Did a quick remix on the chrome-tab script @johnlindquist made so I could quickly navigate to the discussions tab of any repo.

// Description: Open the Discussions pane of a GitHub repo
// Author: Benjamin Lannon
// Twitter: @lannonbr
let { focusTab } = await kit('chrome')
let repo = await arg('Enter repo (ex: johnlindquist/kit):')