@oyster : the source is [text files](https://github.com/nim-lang/Nim/tree/devel/doc/manual) (they are actually rst) which you can convert to pdf with `koch pdf`, it does rst->latex->pdf
If you want a prebuilt version, I built the pdf some time ago: [here](https://github.com/stisa/misc/raw/master/nim-pdfs/manual.pdf) . It should be mostly up to date, as it was built from devel near the release of 0.17.
