[Bug] The spec abstract does not provide a summary of how the DID method works

[swcurran]

Describe the bug
On my first visit to the spec, I'd like to see a concise summary of how the DID Method works -- at least how resolution works, possibly how registration works. I think the current abstract that is a justification for why the DID Method uses a DHT is a missed opportunity.

To Reproduce:

1. Go to the spec.
2. Scroll down to the abstract
3. See that there is no overview of how the DID Method works, nor is there a pointer to such a summary.

Expected behavior:
A clear and concise description of how the DID Method works.