Add contribution section to README file
Add contribution section to README file

Change-Id: I00b96925941ad65d8ce84e23fa4b13e1a885cb3e

stackforge/fuel-plugin-influxdb-grafana,stackforge/fuel-plugin-influxdb-grafana,stackforge/fuel-plugin-influxdb-grafana,stackforge/fuel-plugin-influxdb-grafana