Added -help to the readme
Added -help to the readme

sduskis/cloud-bigtable-examples,sduskis/cloud-bigtable-examples,sduskis/cloud-bigtable-examples,nlpraveennl/cloud-bigtable-examples,nlpraveennl/cloud-bigtable-examples,sduskis/cloud-bigtable-examples,nlpraveennl/cloud-bigtable-examples,GoogleCloudPlatform/cloud-bigtable-examples,sduskis/cloud-bigtable-examples,GoogleCloudPlatform/cloud-bigtable-examples,GoogleCloudPlatform/cloud-bigtable-examples,sduskis/cloud-bigtable-examples,sduskis/cloud-bigtable-examples,GoogleCloudPlatform/cloud-bigtable-examples,nlpraveennl/cloud-bigtable-examples