Briefing for product to process trainee interviews

**Background**
Currently, our process of matching volunteer and trainee availabilities for interviews requires a lot of admin work, and thus we do not expect this process to be scalable once we get more trainees. Therefore, we need to think of a solution to help with this process.

**Acceptance criteria**
Write a briefing for a product that will assist in processing volunteer and trainee availabilities and help in booking the interviews with minimal admin work.