Just add a note [1] right below the title field. There is very little stuff on that submit page. If there are 1-2 sentences, people will read them. [1] E.g.:

Just add a note [1] right below the title field. There is very little stuff on that submit page. If there are 1-2 sentences, people will read them. [1] E.g.: "The title must be the bare title of the linked article. Do not editorialize the title unless it's too long or lacking context."