GlasWolf, The biography of Terry Pratchett by his long-time assistant Rob Wilkins, "A Life in Footnotes", is 99p today at Amazon and Kobo.
It's interesting, surprising, funny, affecting, sad and extremely good
Edit: apparently it's [#TerryPratchettDay today, which explains the timing.]
https://www.kobo.com/gb/en/ebook/terry-pratchett-a-life-with-footnotes