Add DOI from Zenodo to README.md (#33)

Author: eriknw

README.md

@@ -1,10 +1,12 @@
 # **GraphBLAS Algorithms**
 
+[![conda-forge](https://img.shields.io/conda/vn/conda-forge/graphblas-algorithms.svg)](https://anaconda.org/conda-forge/graphblas-algorithms)
 [![pypi](https://img.shields.io/pypi/v/graphblas-algorithms.svg)](https://pypi.python.org/pypi/graphblas-algorithms/)
 [![License](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](https://github.com/python-graphblas/graphblas-algorithms/blob/main/LICENSE)
 [![Tests](https://github.com/python-graphblas/graphblas-algorithms/workflows/Tests/badge.svg?branch=main)](https://github.com/python-graphblas/graphblas-algorithms/actions)
 [![Coverage](https://codecov.io/gh/python-graphblas/graphblas-algorithms/branch/main/graph/badge.svg)](https://codecov.io/gh/python-graphblas/graphblas-algorithms)
-<!--- [![conda-forge](https://img.shields.io/conda/vn/conda-forge/graphblas-algorithms.svg)](https://anaconda.org/conda-forge/graphblas-algorithms) --->
+[![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.7329185.svg)](https://doi.org/10.5281/zenodo.7329185)
+[![Discord](https://img.shields.io/badge/Chat-Discord-blue)](https://discord.com/invite/vur45CbwMz)
 <!--- [![Docs](https://readthedocs.org/projects/graphblas-algorithms/badge/?version=latest)](https://graphblas-algorithms.readthedocs.io/en/latest/) --->
 
 GraphBLAS algorithms written in Python with [Python-graphblas](https://github.com/python-graphblas/python-graphblas).  We are trying to target the NetworkX API algorithms where possible.