Clarify cMCP schema-vote Discussion routing

[solloek369-arch]

cMCP GOVERNANCE.md requires changes to the TRACE Claim schema to go through a GitHub Discussion tagged vote.

CONTRIBUTING.md points design questions and proposals to the AgenTrust organization Discussions, whose source repository is agentrust-io/.github. The current complete .github label registry has no vote label.

What exact Discussion venue/category/tag convention should be used for a cMCP schema vote? If vote is intended to be a Discussion label, could a maintainer create/apply it before the vote is opened?

I am not asking to bypass or start the vote here; I just want to follow the governance mechanism exactly as intended.