Add webfinger to bridgetown.rb

Adding a webfinger to your own domain lets you keep one point of truth for your social media handle. You can tell people to just follow social@matsimitsu.com for example, and through this webfinger file Mastodon will know where to look for your actual profile.

Bridgetown lets you create files with permalinks anywhere. In my case this file is in:

src/webfinger.erb

The contents contain references to my ruby.social account, where my actual Mastodon profile lives, which I can change at any time and anyone using my social@matsimitsu.com reference will end up on the correct instance.

---
sitemap: false
permalink: ".well-known/webfinger"
---

{
  "subject":"acct:matsimitsu@ruby.social",
  "aliases":
  [
      "https://ruby.social/@matsimitsu",
      "https://ruby.social/users/matsimitsu"
  ],
  "links":
  [
      {
          "rel":"http://webfinger.net/rel/profile-page",
          "type":"text/html",
          "href":"https://ruby.social/@matsimitsu"
      },
      {
          "rel":"self",
          "type":"application/activity+json",
          "href":"https://ruby.social/users/matsimitsu"
      },
      {
          "rel":"http://ostatus.org/schema/1.0/subscribe",
          "template":"https://ruby.social/authorize_interaction?uri={uri}"
      }
  ]
}