unity offline installer doesnt have offline scripting API

hello. im fairly new to unity..
im looking forward to actually learn the engine and make a small indie team.
but, i have some problem with scripting API.

here's the thing . in my city internet is not everywhere,and the speed is terrible.
i have see some threads previously ,saying there's a offline scripting API
but, i dont seem to have it pre-installed with the offline installer.

i download the unity with torrent, not the online installer.

here's my question: how am i able to find unity offline API in pdf or docs or any other form so i dont have to open the internet for scripting API, pdf is preferred ,but docs is fine to .. thanks beforehand,, MoJo

 

Download the Unity installer, then choose to download and install only the documentation.

 

I dont know i can do that .
Thanks bruh