[dividuum]

I really like the Lua reference manual. All on a single page (e.g. https://www.lua.org/manual/5.3/manual.html), covers the complete syntax/semantic of the language, a few concepts as well as its Lua and C embedding APIs. All without bells and whistles. It surely helps that it's a relatively easy language. While I learned Lua, I basically never had to look anywhere else for information. I guess that's what a good documentation is supposed to aim for.