introduction rewrite

[dickhardt]

provide more context on what the problem is and why this work is happening, with a summary of how it works

deleted spurious language that reads like a patent application

[rohanmahy]

I am generally OK with a much more concise introduction (but I don't find the current Introduction offensive either). If we were to use a shorter intro I would want to see the following addressed:

1. Mention that you can create an SD-JWT for an arbitrary JWS (not just a JWT).
2. Reintroduce a casual introduction of the terms "Claims" and "Disclosures", as this was very useful
3. Spell out SD-JWT on first use
4. s/the verifier would like assurance/the holder can optionally provide assurance/
5. Add back this sentiment "While JWTs with claims describing natural persons are a common use case, the mechanisms defined in this document are also applicable to other use cases."

[bc-pi]

Thanks @rohanmahy, I generally agree with that.

Note that @danielfett has kindly (foolishly?) said he'd take a pass at reviewing or refining or rewriting or reworking this and/or the current (unoffensive, thanks!) Introduction.

[bc-pi]

The github UX tells me that I "need to leave a comment indicating the requested changes."

[bc-pi]

Note that @danielfett has kindly (foolishly?) said he'd take a pass at reviewing or refining or rewriting or reworking this and/or the current (unoffensive, thanks!) Introduction.

see #477 for that

[Sakurann]

supeceded by #477