improve(cockpit-sample-plugin): edit README
improve(cockpit-sample-plugin): edit README

Related to CAM-7020

camunda/camunda-bpm-examples,camunda/camunda-bpm-examples,ingorichtsmeier/camunda-bpm-examples,camunda/camunda-bpm-examples,ingorichtsmeier/camunda-bpm-examples,camunda/camunda-bpm-examples,ingorichtsmeier/camunda-bpm-examples