governance docs should spell out that contributors should be competent

i don't think we have anything that says 'before you make a proposal, try not to be out of your depth'. it might be worth gently adding

No file, test, or documentation entry point is named. Locate the governance documentation and review its existing contributor guidance first; the work is done when it clearly and gently explains the expected level of competence before making a proposal.

Written by the indexing model from the issue text.