Fixing docs to reflect proper withRedis usage

[divideby0]

According to our experience, this call fails:

redisService.withRedis {
   redis.exists "someKey"
}

When we do this, we get the following exception:

Caused by MissingPropertyException: No such property: redis for class: stufftodo.ChicagoReaderEventSearchService
->>  26 | doCall in foo.BarService$_baz_closure1$$ENcncclc
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
|    76 | withRedis in grails.plugin.redis.RedisService
|    25 | shouldUpdate in foo.BarService$$ENcncclc
|    39 | handleMessage in     ''
^   680 | run in java.lang.Thread

However, when we call:

redisService.withRedis { Jedis redis ->
   redis.exists "someKey"
}

Everything works as expected. This pull request updates the README to reflect proper API usage.

If we're mistaken and the first example should work as expected, we may have hit a bug.

[tednaleid]

+1 thanks! Yep, that was an error in the documentation, thanks for fixing it!