Updated README to reflect proper usage of --project_id flag
Updated README to reflect proper usage of --project_id flag

Updated README to reflect proper usage of --project_id flag when
loading data. Although, not entirely sure why it is only with “bq load”
that you have to use —project_id= yet the rest of the times bq uses
—project=.

GoogleCloudPlatform/PerfKitExplorer,GoogleCloudPlatform/PerfKitExplorer,GoogleCloudPlatform/PerfKitExplorer,GoogleCloudPlatform/PerfKitExplorer