Update contribution_guide.md
Update contribution_guide.md

Added info in 'how to check' parts
Fiware/context.Orion,McMutton/fiware-orion,telefonicaid/fiware-orion,jmcanterafonseca/fiware-orion,telefonicaid/fiware-orion,Fiware/context.Orion,jmcanterafonseca/fiware-orion,telefonicaid/fiware-orion,McMutton/fiware-orion,telefonicaid/fiware-orion,jmcanterafonseca/fiware-orion,Fiware/context.Orion,Fiware/data.Orion,McMutton/fiware-orion,telefonicaid/fiware-orion,McMutton/fiware-orion,Fiware/context.Orion,McMutton/fiware-orion,jmcanterafonseca/fiware-orion,telefonicaid/fiware-orion,McMutton/fiware-orion,McMutton/fiware-orion,Fiware/context.Orion,Fiware/data.Orion,jmcanterafonseca/fiware-orion,Fiware/data.Orion,Fiware/data.Orion,Fiware/data.Orion,Fiware/data.Orion,jmcanterafonseca/fiware-orion,Fiware/context.Orion