A digital object identifier (DOI) is key to uniquely identify a piece of software as well as the specific releases, in turn the basis for reproducibility. Getting a DOI for your software in Zenodo is straight forward due to its nice integration and HowTo guides:
Additionally, consider adding a CITATION file to the repository once it is availbale in Zenodo:
Once you do the above, you can add a badge with the DOI to the repo, as well.