docs: Document language setting

Author: oliversalzburg

packages/documentation/docs/sections/internals.md

@@ -10,6 +10,12 @@ By default, this is `2000` milliseconds, which is `2` seconds.
 
     Lowering this value can cause instability or freeze your game, because so many browser resources will be spent on KS. If you want to speed up KS, lower the interval gradually.
 
+## Language
+
+Allows you to select a language different from the language used in KG.
+
+Initially, KS will just use the language KG is set at, but you can override this language here.
+
 <!-- prettier-ignore-start -->
 *[JS]: JavaScript
 *[KG]: Kittens Game