DOC: Update Python package documentation for GitHub Actions

Author: thewtex

README.md

@@ -97,14 +97,15 @@ followlowing contents:
       GIT_TAG abcdef012345
       )
 
-Python Packages
----------------
+CI Testing and Python Packages
+------------------------------
 
 Continuous integration service configurations are included to build
+and test the C++ core of packages across platforms and build binary
 Python packages for Linux, macOS, and Windows. These packages can be
-[downloaded](https://itkpythonpackage.readthedocs.io/en/latest/Build_ITK_Module_Python_packages.html#github-automated-ci-package-builds)
+[downloaded](https://itkpythonpackage.readthedocs.io/en/master/Build_ITK_Module_Python_packages.html#github-automated-ci-package-builds)
 and [uploaded to the Python Package Index
-(PyPI)](https://itkpythonpackage.readthedocs.io/en/latest/Build_ITK_Module_Python_packages.html#upload-the-packages-to-pypi).
+(PyPI)](https://itkpythonpackage.readthedocs.io/en/master/Build_ITK_Module_Python_packages.html#upload-the-packages-to-pypi).
 
 ITKv4 Branch
 ------------