Add links in README

Author: thewtex

README.md

@@ -1,2 +1,6 @@
 # ITKPythonBuilds
-Binary builds of ITK from Python package generation. For building ITK external module Python packages.
+
+Binary builds of [ITK](https://itk.org/) from [its Python
+package](https://pypi.python.org/pypi/itk) generation. These are used to build
+[ITK external module Python
+packages](https://itkpythonpackage.readthedocs.io/en/latest/).