Update example in the README

Update the example to have a sensible value for the threads property

README.md

@@ -102,7 +102,7 @@ Follow the steps here and configure the presto-yarn configuration files to match
 * ``site.global.additional_node_properties`` and ``site.global.additional_config_properties`` (optional) (default - None): Presto launched via Slider will use ``config.properties`` and ``node.properties`` created from templates ``presto-yarn-package/package/templates/config.properties*.j2`` and ``presto-yarn-package/package/target/node.properties.j2`` respectively. If you want to add any additional properties to these configuration files, add ``site.global.additional_config_properties`` and ``site.global.additional_node_properties`` to your ``appConfig.json``. The value of these has to be a string representation of an array of entries (key=value) that has to go to the ``.properties`` file. Eg:
 
 ```
-    "site.global.additional_config_properties": "['task.max-worker-threads=5', 'distributed-joins-enabled=true']"
+    "site.global.additional_config_properties": "['task.max-worker-threads=50', 'distributed-joins-enabled=true']"
 ```    
 
 * ``site.global.plugin`` (optional) (default - None): This allows you to add any additional jars you want to copy to plugin ``presto-server-<version>/plugin/<connector>`` directory in addition to what is already available there. It should be of the format {'connector1' : ['jar1', 'jar2'..], 'connector2' : ['jar3', 'jar4'..]..}. This will copy jar1, jar2 to Presto plugin directory at plugin/connector1 directory and jar3, jar4 at plugin/connector2 directory. Make sure you have the plugin jars you want to add to Presto available at ```presto-yarn-package/src/main/slider/package/plugins/``` prior to building the presto-yarn app package and thus the app package built ``presto-yarn-package-<version>-<presto-version>.zip`` will have the jars under ```package/plugins``` directory.