error[preamble-author]: authors in the preamble must match the expected format --> input.md:5:8 | 5 | author: John Doe a | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unrecognized author | = help: Try `Random J. User (@username) ` for an author with a GitHub username plus email. = help: Try `Random J. User (@username)` for an author with a GitHub username. = help: Try `Random J. User ` for an author with an email. = help: Try `Random J. User` for an author without contact information. error[preamble-author]: preamble header `author` must contain at least one GitHub username --> input.md | 5 | author: John Doe a |