Add disk type examples to README.md
Add disk type examples to README.md

GoogleCloudPlatform/PerfKitBenchmarker,AdamIsrael/PerfKitBenchmarker,AdamIsrael/PerfKitBenchmarker,meteorfox/PerfKitBenchmarker,GoogleCloudPlatform/PerfKitBenchmarker,meteorfox/PerfKitBenchmarker,GoogleCloudPlatform/PerfKitBenchmarker,GoogleCloudPlatform/PerfKitBenchmarker