RC-1 and Beta-1 release notes

[iamsamirzon]

This is the first Release Candidate for Notary V2. It will include release from all the repositories for Notary v2 project.

• notaryproject/notaryproject for the specification
• notaryproject/notation for the CLI tool
  • notaryproject/notation-go for the sign/verify library
  • notaryproject/notation-core-go for the basic crypto operations