Update package.json

src/server.js doesn't exist, so won't load with require('json-server').

Author: Patrick Heneise

package.json

@@ -2,7 +2,7 @@
   "name": "json-server",
   "version": "0.5.2",
   "description": "Serves JSON files through REST routes.",
-  "main": "./src/server.js",
+  "main": "./src/index.js",
   "bin": "./bin/index.js",
   "directories": {
     "test": "test"