Council may by general ordinance provide for legislative procedure; the form and method of enactment of ordinances; a simplified procedure for levying assessments; the method and manner of giving public notice of the passage of ordinances or resolutions of a general or permanent nature; the advertisement and sale of bonds and notes; and the advertisement and awarding of public contracts. Such general ordinances, when once adopted, shall not be repealed or amended except by vote of five (5) members of Council or by the people.