Add license to specification text

[imphil]

The trace specification document doesn't contain any license statement, even though the repository says it's CC-BY 4.0. Could you add this information to the specification itself?

[cetola]

Hey @imphil, sorry this issue has dragged on a bit. We're currently reviewing how we generate specifications for RISC-V and the copyright / software licenses that we will be using as best practices. For now we are not going to update the repo, but know that this will be addressed long term.