docs(README): update doc link to connection options

Author: luin

README.md

@@ -189,7 +189,7 @@ new Redis("redis://:[email protected]:6380/4");
 new Redis("redis://username:[email protected]:6380/4");
 ```
 
-See [API Documentation](http://luin.github.io/ioredis/classes/index.html#RedisOptions) for all available options.
+See [API Documentation](http://luin.github.io/ioredis/index.html#RedisOptions) for all available options.
 
 ## Pub/Sub