Expose VM count and scratch disk requirements in help.
Expose VM count and scratch disk requirements in help.

GoogleCloudPlatform/PerfKitBenchmarker,kivio/PerfKitBenchmarker,emaeliena/PerfKitBenchmarker,tvansteenburgh/PerfKitBenchmarker,ehankland/PerfKitBenchmarker,GoogleCloudPlatform/PerfKitBenchmarker,lleszczu/PerfKitBenchmarker,lleszczu/PerfKitBenchmarker,syed/PerfKitBenchmarker,meteorfox/PerfKitBenchmarker,AdamIsrael/PerfKitBenchmarker,mateusz-blaszkowski/PerfKitBenchmarker,GoogleCloudPlatform/PerfKitBenchmarker,syed/PerfKitBenchmarker,emaeliena/PerfKitBenchmarker,gablg1/PerfKitBenchmarker,askdaddy/PerfKitBenchmarker,mateusz-blaszkowski/PerfKitBenchmarker,tvansteenburgh/PerfKitBenchmarker,kivio/PerfKitBenchmarker,GoogleCloudPlatform/PerfKitBenchmarker,AdamIsrael/PerfKitBenchmarker,ksasi/PerfKitBenchmarker,juju-solutions/PerfKitBenchmarker,juju-solutions/PerfKitBenchmarker,ehankland/PerfKitBenchmarker,ksasi/PerfKitBenchmarker,meteorfox/PerfKitBenchmarker,msurovcak/PerfKitBenchmarker,msurovcak/PerfKitBenchmarker,askdaddy/PerfKitBenchmarker,gablg1/PerfKitBenchmarker