adding joss badge!

Signed-off-by: vsoch <[email protected]>

Author: vsoch

README.md

@@ -2,6 +2,8 @@
 
 [![GitHub actions status](https://github.com/singularityhub/singularity-hpc/workflows/singularity-hpc/badge.svg?branch=main)](https://github.com/singularityhub/singularity-hpc/actions?query=branch%3Amain+workflow%3Asingularity-hpc)
 [![DOI](https://zenodo.org/badge/354130612.svg)](https://zenodo.org/badge/latestdoi/354130612)
+[![DOI](https://joss.theoj.org/papers/10.21105/joss.03311/status.svg)](https://doi.org/10.21105/joss.03311)
+
 
 ![https://raw.githubusercontent.com/singularityhub/singularity-hpc/main/docs/assets/img/shpc.png](https://raw.githubusercontent.com/singularityhub/singularity-hpc/main/docs/assets/img/shpc.png)