Proposing a P2QRH BIP towards a quantum resistant soft fork

The recent update to the specification now includes FALCON, following Antoine's suggestions. This addition is significant as it incorporates a section specifically dedicated to discussing the implications of integrating two different post-quantum cryptosystems, which notably increases the maintenance requirements. For a detailed review of these changes, one can refer to the proposed modifications directly at the GitHub pull request. This adjustment reflects a thoughtful consideration of feedback and an effort to enhance the system's resilience against future cryptographic challenges.