Update contribution guidelines
Update contribution guidelines

Ibercheck/api-docs,claylo/api-docs,claylo/api-docs,ProcessOut/documentation,claylo/api-docs,linchpinio/docs,Ibercheck/api-docs,linchpinio/docs,bookiza/docs,kasko/docs,bookiza/docs,linchpinio/docs,bookiza/docs,bookiza/docs,ProcessOut/documentation,ProcessOut/documentation,Ibercheck/api-docs