Add versioning notes to changelog

Author: softwareengineerprogrammer

CHANGELOG.rst

@@ -106,3 +106,19 @@ Internal changes to support unit testing
 ------------
 
 * `GEOPHIRES v1 </References/Beckers%202013%20GEOPHIRES%20v1.pdf>`__
+
+
+Versioning Notes
+----------------
+
+GEOPHIRES 3.0 (GEOPHIRES-X) and subsequent releases use `semantic versioning <https://en.wikipedia.org/wiki/Software_versioning#Semantic_versioning>`__.
+Major, minor, and notable patch versions are documented above.
+You may also be interested in viewing the list of all PRs merged into the repository `here <https://github.com/NREL/GEOPHIRES-X/pulls?q=is%3Apr+is%3Amerged+>`__.
+
+Each semantic version has a corresponding tag, the full list of which can be viewed `here <https://github.com/NREL/GEOPHIRES-X/tags>`__.
+The latest patch version in this repository and patch versions explicitly mentioned in this changelog are always suitable for public consumption;
+but note that not all patch version tags in the list are meant for public consumption
+as intermediate internal-only patch versions are sometimes introduced during the development process.
+(Improved designation and distribution of releases for public consumption may eventually be addressed by
+`publishing to PyPI <https://github.com/NREL/GEOPHIRES-X/issues/117>`__ and/or use of
+`GitHub releases <https://docs.github.com/en/repositories/releasing-projects-on-github/about-releases>`__.)