feat: update types in package.json

Signed-off-by: Carson Farmer <carson.farmer@gmail.com>

Author: carsonfarmer

package.json

@@ -4,6 +4,7 @@
   "description": "CID Implementation in JavaScript",
   "leadMaintainer": "Volker Mische <volker.mische@gmail.com>",
   "main": "src/index.js",
+  "types": "src/index.d.ts",
   "scripts": {
     "lint": "aegir lint",
     "test": "aegir test",