feat: add lua-fenster (#147)

Author: jonasgeiler

.gitmodules

@@ -177,3 +177,6 @@
 [submodule "addons/RavenscriptIDEA_withRavenM/module"]
 	path = addons/RavenscriptIDEA_withRavenM/module
 	url = https://github.com/RavenfieldCommunity/ravenscriptidea
+[submodule "addons/fenster/module"]
+	path = addons/fenster/module
+	url = https://github.com/jonasgeiler/lua-fenster-type-definitions.git

addons/fenster/info.json

@@ -0,0 +1,5 @@
+{
+  "$schema": "https://raw.githubusercontent.com/LuaLS/LLS-Addons/main/schemas/addon_info.schema.json",
+  "name": "lua-fenster",
+  "description": "Definitions for the lua-fenster library."
+}