build: include typings

Author: yeikos

package.json

@@ -4,7 +4,9 @@
 	"author": "yeikos",
 	"description": "(recursive)? merging of (cloned)? objects.",
 	"main": "lib/src/index.js",
-	"files": [],
+	"files": [
+		"lib/src/index.d.ts"
+	],
 	"license": "MIT",
 	"homepage": "https://github.com/yeikos/js.merge",
 	"repository": {