Update CONTRIBUTING.md
Update CONTRIBUTING.md

fix one typo
ashagnanasekar/friendly_id,MAubreyK/friendly_id,ThanhKhoaIT/friendly_id,Pathgather/friendly_id,MatthewRDodds/friendly_id,joshsoftware/friendly_id,kangkyu/friendly_id,norman/friendly_id,onursarikaya/friendly_id,morsedigital/friendly_id