Impact of SNARK on Mithril protocol security

## Why
We want to assess and document the impact of the SNARK implementation on the security of Mithril protocol. 

## What
Assess and document the impact of the SNARK in Mithril security

## How 

- [ ] Impact on the security of the protocol
- [ ] Update security page 
- [ ] Update threat model
- [ ] Post quantum security assessment?
