Updated CONTRIBUTING.md
Updated CONTRIBUTING.md

Added myself on the contributors' list.

strongbox/strongbox,sbespalov/strongbox,nenko-tabakov/strongbox,AlexOreshkevich/strongbox,sbespalov/strongbox,ivanursul/strongbox,sbespalov/strongbox,baisjuan/strongbox,strongbox/strongbox,ivanursul/strongbox,sbespalov/strongbox,strongbox/strongbox,strongbox/strongbox,korest/strongbox