Add HeadStart (NDSS Symposium 2022)

[LeeXun]

This pull request proposes to add the paper and video links of HeadStart, a VDF-based randomness generation protocol published at NDSS Symposium 2022.

• HeadStart is an efficiently verifiable and low-latency participatory randomness generation protocol with high usability and scalability.
• We evaluated HeadStart through analysis and experiments. The results confirm that HeadStart is scalable and can be efficiently verified on commodity devices.
• We presented ClHash: an efficient algorithm that hashes to a class group of an imaginary quadratic field.

Thank you!