On a shared note, select text and click Suggest (the pen in the selection toolbar): write what it should say instead (or leave it empty to suggest deleting it), and why if you like. People who can only view the note can suggest too.
Suggestions show in the comments panel, the old text struck through and the new text beside it. Someone who can edit the note clicks Accept to make the change, or Reject; either way the thread is resolved, and everyone sees who decided.
If the text changed since, a suggestion can't be applied: reject it, or make the change yourself.