correct require() export

I'd meant to update the types to point to index.d.ts, and inadvertently
changed the *export* to index.js instead, whoops.

Re: #503

Author: isaacs

package.json

@@ -17,8 +17,8 @@
         "default": "./dist/mjs/index.js"
       },
       "require": {
-        "types": "./dist/cjs/index-cjs.d.ts",
-        "default": "./dist/cjs/index.js"
+        "types": "./dist/cjs/index.d.ts",
+        "default": "./dist/cjs/index-cjs.js"
       }
     }
   },