I once read that writing documentation is writing a love letter to a future you. (Check out – https://quotefancy.com/quote/1729031/Damian-Conway-Documentation-is-a-love-letter-that-you-write-to-your-future-self for the proper quote.) But it is frustrating that so few write documentation now. If I had any concerns about Agile, the misunderstanding about documentation is one of them. Developers mostly just want to get stuck in coding and any excuse not to write documentation is snapped up. It doesn’t need to be an onerous task. Just think about what you would like explained if you had to pick up the code cold in a couple of years (or weeks and months.) What would you like to know? What would help you understand what you were trying to achieve, and why you did it this way? Start with that.