Novice guide

Here are some links I found useful.

Basics:
By rezecib - Getting started with modding DST (and some general tips for DS as well)

https://forums.kleientertainment.com/forums/topic/47353-guide-getting-started-with-modding-dst-and-some-general-tips-for-ds-as-well/#StartWithAnotherMod

Programming in Lua (first edition):

https://www.lua.org/pil/contents.html#P1

Advanced things:
By PeterA - net_variable types and sending data from server/host to clients:

https://forums.kleientertainment.com/forums/topic/48264-net_variable-types-and-sending-data-from-serverhost-to-clients/

By tetrified - Intro to worldgen

https://forums.kleientertainment.com/forums/topic/48070-guide-intro-to-worldgen/