added public domain to README

README.rst

@@ -85,3 +85,12 @@ Acknowledgements
 ----------------
 The package template used by this package is based on the one developed by the
 `OpenAstronomy community <https://openastronomy.org>`_ and the `SunPy Project <https://sunpy.org/>`_.
+
+Public Domain
+-------------
+
+This project constitutes a work of the United States Government and is not subject to domestic copyright protection under `17 USC § 105 <https://www.govinfo.gov/app/details/USCODE-2010-title17/USCODE-2010-title17-chap1-sec105>`__. Additionally, we waive copyright and related rights in the work worldwide through the `CC0 1.0 Universal public domain dedication <https://creativecommons.org/publicdomain/zero/1.0/>`__.
+
+All contributions to this project will be released under the CC0
+dedication. By submitting a pull request, you are agreeing to comply
+with this waiver of copyright interest.