Fix invalid main field

Author: Munter

package.json

@@ -2,7 +2,7 @@
   "name": "tap-spot",
   "version": "1.1.1",
   "description": "Compact dot reporter for TAP output. Supports skip and todo",
-  "main": "./bin/dot.js",
+  "main": "./index.js",
   "repository": {
     "type": "git",
     "url": "https://github.com/Munter/tap-spot.git"