🐞 Add new EG spec, data serialization spec, and release notes

[jungshadow]

Is there an existing issue for this?

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Current Behavior

The new EG spec, data serialization spec, and release notes are not on the site.

Expected Behavior

The new EG spec, data serialization spec, and release notes should be on the site.

Steps To Reproduce

No response

Environment

- OS:

Anything else?

There is a new EGv2.1 design specification and a first draft of the data serialization specification. The latter is essential for anyone writing a compatible implementation or a verifier. The design says what has to be done, how, and why. The data serialization spec describes the data formats used in our implementation to achieve the design. The data serialization spec currently matches the v2.0 implementation but should be updated to match v2.1 within the next few weeks. Additionally, the release notes need to be added to the site to describe the changes to the specification.