ResearchEquals Policy: Updating research outputs transparently

This document sets out how ResearchEquals versions research outputs and applies updates to DOIs in Crossref metadata (i.e., [Crossmark Policy](https://www.crossref.org/documentation/crossmark/participating-in-crossmark#00280)). In short, we provide one Digital Object Identifier (DOI) per version and have one DOI that always points to the latest version (akin to the versioning done by [Zenodo](https://zenodo.org/help/versioning)). Each version is marked using [Semantic Versioning](https://semver.org/) and optionally accompanied by a CHANGELOG (as provided by the author). This version history is included alongside each version of the output, to provide a clear contextual view of the research on display. All versions >1.0.0 result in the DOI metadata being marked with a new version. Our policy on versioning outputs transparently solidifies our commitment to allow for knowledge to evolve in flexible manners. Further work is needed to create something akin to editorial oversight of the research shared on ResearchEquals that has the option to add expressions of concern, retractions, and other updates.