documented resolvers

docs/backend/api.md

docs/backend/api/GroupResolver.md

docs/backend/api/ItemDocumentResolver.md

docs/backend/api/ItemResolver.md

docs/backend/api/MemberResolver.md

docs/backend/api/RentalResolver.md

docs/backend/api/StorageResolver.md

docs/backend/api/UserResolver.md

docs/backend/api/template.md

docs/backend/models/Rental.md

docs/readme.md

server/src/modules/storage/StorageResolver.ts