update contributing section
update contributing section

sagalbot/vue-select,Vinelab/vue-select-checkbox,fazo96/vue-select-extended,akkinenirajesh/vue-select,fazo96/vue-select-extended,sagalbot/vue-select,akkinenirajesh/vue-select,rinterliche/vue-select,rinterliche/vue-select,Vinelab/vue-select-checkbox