Fix contributing.md.
Fix contributing.md.

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