README: add PyPI info

Author: dlech

README.md

@@ -6,6 +6,19 @@ This is a community-supported version of the unmaintained [winrt] package.
 
 [winrt]: https://pypi.org/project/winrt
 
+
+## Installation
+
+This package is distributed on PyPI as the [winsdk] package.
+
+    # use your favorite environment manager
+    poetry add winsdk
+    pipenv install winsdk
+    pip install winsdk
+
+[winsdk]: https://pypi.org/project/winsdk
+
+
 ## Documentation
 
 Since the bindings are automatically generated, there are no API docs available.