"Course ratings" plugin allows students to add ratings and reviews to the courses, and teachers and other users to read them.
The custom course field that stores the average course rating is created automatically. The course ratings will be displayed in any course listing that displays custom course fields, for example, "All courses" page and site home.
The current course rating is also automatically added to each course home page.
Managers are able to permanently delete course reviews that were flagged by users.
By default every student enrolled into a course can leave a rating. It can be configured that only students who completed the course can do it. There is also an option to allow to enable or disable course ratings for individual courses.
This plugin can be found in Moodle plugins directory: https://moodle.org/plugins/tool_courserating