Create a clang-area-team GitHub repo

The @llvm/clang-area-team would like a top-level git repository to organize our efforts. Specifically, we'd like a place to house our meeting minutes as well as a dedicated issue list where we can track the status of RFCs. Note, we're not proposing (currently) to run the RFC process through GitHub. RFCs will continue through Discourse, but each Clang-related RFC will get an issue in this new repo to track administrative state of the RFC. We may also use this as a place to store scripts for things like helping maintain the maintainers list, etc.

No files or tests are named. Start by reviewing the requested repository scope and existing LLVM team-management conventions; define the repository’s meeting-minutes and RFC-tracking responsibilities, while keeping RFC discussion on Discourse. Done means the top-level repository exists with a clear structure and an agreed administrative tracking workflow.

Written by the indexing model from the issue text.