Update README for new version

Author: imbstack

README.md

@@ -8,15 +8,14 @@ A Javascript client library for [statsum](https://github.com/jonasfj/statsum).
 
 let Statsum = require('statsum');
 
-// Create a project token
-let token = Statsum.createToken('my-project', 'SECRET', '24h');
-
 // Create a client object
-let statsum = new Statsum({
-  project:  'my-project',
-  token:    token,
-  baseUrl:  'https://statsum.example.com',
-});
+let configurer = async (project) => { return {
+  project: 'example-project',
+  baseUrl: 'https://example.com',
+  token: 'KEY',
+  expires: new Date().toJSON()
+}};
+let statsum = new Statsum(configurer, {project: 'test'});
 
 // Send metrics
 statsum.count('my-counter', 1);

src/client.js

@@ -11,7 +11,7 @@ class StatsumClient extends events.EventEmitter {
   /**
    * Create a statsum client.
    *
-   * Configurer: A function that returns an object like
+   * Configurer: A function that must return an object with these specific keys
    * ```js
    * {
    *   project:       '...',                  // Project to submit for