docs: add Factorio Type Kit

Factorio Type Kit hosts factorio declarations!

Author: cdaringe

docs/getting-started.md

@@ -80,3 +80,4 @@ The real power of this transpiler is usage together with good declarations for t
 - [LÖVE 2D Game Development](https://github.com/hazzard993/love-typescript-definitions)
 - [World of Warcraft - Addon Development](https://github.com/wartoshika/wow-declarations)
 - [World of Warcraft Classic - Addon Development](https://github.com/wartoshika/wow-classic-declarations)
+- [Factorio Type Kit](https://cdaringe.github.io/factorio-type-kit/)