Updated docker commands in README (#458)
Updated docker commands in README (#458)

Addresses #452
open-telemetry/opentelemetry-collector-contrib,open-telemetry/opentelemetry-collector,census-instrumentation/opencensus-service,census-instrumentation/opencensus-service,open-telemetry/opentelemetry-collector-contrib,open-telemetry/opentelemetry-collector,open-telemetry/opentelemetry-collector