updated single_source_version with a much simpler page -- essentially

refering folks to their build system of choice.

Author: ChrisBarker-NOAA

source/single_source_version.rst

@@ -0,0 +1,51 @@
+.. _`Single sourcing the version`:
+
+===================================
+Single-sourcing the Project Version
+===================================
+
+:Page Status: Complete
+:Last Reviewed: 2015-09-08
+
+One of the challenges in building packages is that the version string can be required in multiple places.
+
+* It needs to be specified when building the package (e.g. in pyproject.toml)
+   - That will assure that it is properly assigned in the distribution file name, and in teh installed package.
+
+* Some projects require that there be a version string available as an attribute in the importable module, e.g::
+
+    import a_package
+    print(a_package.__version__)
+
+While different projects have different needs, it's important to make sure that there is a single source of truth for the version number.
+
+In general, the options are:
+
+1) If the code is in a version control system (VCS), e.g. git, then the version can be extracted from the VCS.
+
+2) The version can be hard-coded into the `pyproject.toml` file -- and the build system can copy it into other locations it may be required.
+
+3) The version string can be hard-coded into the source code -- either in a special purpose file, such as `_version.txt`, or as a attribute in the `__init__.py`, and the build system can extract it at build time.
+
+If the version string is not in the source, it can be extracted at runtime with code in `__init__.py`, such as::
+
+    import importlib.metadata
+    __version__ = importlib.metadata.version('the_distribution_name')
+
+
+Consult your build system documentation for how to implement your preferred method.
+
+Put links in to build system docs?
+-- I have no idea which are currently robust and maintained -- do we want to get into seeming endorsing particular tools in this doc?
+
+
+* setuptools:
+
+* hatch:
+
+* poetry:
+
+* PyBuilder:
+
+* Others?
+