@actions/artifact download artifacts (#340)

* Download Artifacts using @actions/artifact

package.json

@@ -10,8 +10,8 @@
   ],
   "homepage": "https://github.com/actions/toolkit/tree/master/packages/artifact",
   "license": "MIT",
-  "main": "lib/artifact.js",
-  "types": "lib/artifact.d.ts",
+  "main": "lib/artifact-client.js",
+  "types": "lib/artifact-client.d.ts",
   "directories": {
     "lib": "lib",
     "test": "__tests__"