Reworking sections

[identitymonk]

I propose to have sections more aligned with NIST SP 800-63:

• BCP
  • Definition of considered authenticators: Definition, characteristics, requirements for enrollment, management,and usage
  • Definition of supporting component for authentication: Definition, characteristics, requirements for enrollment, management,and usage
• Maturity Model: Definition, eligible authenticator, eligible supporting components
  • We should limit at 4, 3 is even better to match other xAL
• Security section about threats and mitigations