First draft of ActivityPub HTML Discovery report

Hello, all. There's a first draft of the ActivityPub HTML Discovery 
report here:

https://swicg.github.io/activitypub-html-discovery/

It includes:

  * a description of discovery as a topic
  * motivating use cases for HTML-to-ActivityPub discovery and
    ActivityPub-to-HTML discovery
  * techniques for discovering equivalent objects and authors
  * verification techniques for object discovery and author discovery
  * best practices for consumers and publishers

It would be great to collect issues here:

https://github.com/swicg/activitypub-html-discovery/issues

At least one major feature still needs to be written up -- discovering 
equivalent actors using rel="me". Tantek, can we work on this together?

Evan