Add JOSS paper badge to README

Author: gattia

README.rst

@@ -4,14 +4,23 @@ Python-CPD
 
 .. |master_badge| image:: https://github.com/siavashk/pycpd/actions/workflows/build-test.yml/badge.svg?branch=master
 .. |development_badge| image:: https://github.com/siavashk/pycpd/actions/workflows/build-test.yml/badge.svg?branch=development
+.. |joss_paper_badge| image:: https://joss.theoj.org/papers/10.21105/joss.04681/status.svg
+   :target: https://doi.org/10.21105/joss.04681
 
++-----------------+---------------------+
+| Paper Citation  | |joss_paper_badge|  |
++-----------------+---------------------+
+
++-----------------+---------------------+
+|            Build Status               |
 +-----------------+---------------------+
 | master          | |master_badge|      |
 +-----------------+---------------------+
 | development     | |development_badge| |
 +-----------------+---------------------+
 
 
+
 `Documentation <https://siavashk.github.io/pycpd/>`_
 
 Pure Numpy Implementation of the Coherent Point Drift Algorithm.
@@ -200,4 +209,4 @@ Contributions are welcome. Please see the guidelines outlined in the document: `
 ***************
 Code of Conduct
 ***************
-We have adopted the code of conduct defined by the `Contributor Covenant <https://www.contributor-covenant.org/>`_ to clarify expected behavior in our community. For more information see the `Code of Conduct <https://github.com/siavashk/pycpd/blob/master/CODE_OF_CONDUCT.md>`_.
+We have adopted the code of conduct defined by the `Contributor Covenant <https://www.contributor-covenant.org/>`_ to clarify expected behavior in our community. For more information see the `Code of Conduct <https://github.com/siavashk/pycpd/blob/master/CODE_OF_CONDUCT.md>`_.