Add a method that requires only metadata updates

[gadenbuie]

I originally prototyped using metadata only, e.g.

---
bluesky-comments: https://bsky.app/profile/grrrck.xyz/post/3lbu5opiixc2j
---

but the problem is that it gets tricky to put the comments section in the right place if you need to do additional customization.

I think it'd be a good idea to follow the listings approach and have the comments appear at the end of the main content or to be placed in an id container. Maybe something like this...

---
bluesky-comments: 
  post: https://bsky.app/profile/grrrck.xyz/post/3lbu5opiixc2j
  id: comments
  before: |
    ---
    
    ## Comments

  after: "Something here?"
---