Improve Example Handling

[wip-abramson]

When a spec includes an example, e.g. a JSON object, these examples should be autonumbered and easily referenced throughout the spec and externally linked to.

See this example from DID Core using ReSpec - https://www.w3.org/TR/did/upcoming/#example-did-document-with-1-verification-method-type.

The example has:

• A user provided ID - #example-did-document-with-1-verification-method-type
• An autogenerated number (Example 24)
• A title
• A clickable and copyable link to this example within the example title
• Clearly styled separation of the example from the rest of the spec text

[KDean-Dolphin]

This is under investigation. There's a Pandoc filter available, but it doesn't play well with npm.