adding zenodo badge and citation.cff

Signed-off-by: vsoch <vsoch@users.noreply.github.com>

CITATION.cff

@@ -0,0 +1,9 @@
+cff-version: 1.1.0
+message: "If you use this software, please cite it as below."
+authors:
+  - family-names: Vanessa
+    given-names: Sochat
+    orcid: https://orcid.org/0000-0002-4387-3819
+title: rseng/rseng: Research Software Encyclopedia Criteria and Taxonomy v0.0.18
+version: 0.0.18
+date-released: 2021-10-07

README.md

@@ -2,6 +2,7 @@
 
 [![PyPI version](https://badge.fury.io/py/rseng.svg)](https://badge.fury.io/py/rseng)
 [![https://img.shields.io/badge/rseng-project-purple](https://img.shields.io/badge/rseng-project-purple)](https://rseng.github.io/) [![https://good-labs.github.io/greater-good-affirmation/assets/images/badge.svg](https://good-labs.github.io/greater-good-affirmation/assets/images/badge.svg)](https://good-labs.github.io/greater-good-affirmation)
+[![DOI](https://zenodo.org/badge/271359724.svg)](https://zenodo.org/badge/latestdoi/271359724)
 
 Criteria and taxonomy for research software engineering (rseng).