add doc about packaging

PACKAGING.md

@@ -0,0 +1,34 @@
+# Packaging of hapic
+
+## Prerequisite
+
+Prepare a `~/.pypirc` configuration file, eg:
+
+    [distutils]
+    index-servers = pypi
+
+    [pypi]
+    repository: https://upload.pypi.org/legacy/
+    username: algoo
+
+Upgrade or install packages:
+
+    pip install --upgrade setuptools wheel twine
+
+## Package and distribute
+
+Checkout on branch `master` (or other branch if you know what you are doing):
+
+    git checkout master
+
+Build the package:
+
+    python setup.py sdist
+
+Upload it:
+
+    twine upload dist/*
+
+If you want give a try before, use:
+
+    twine upload --repository-url https://test.pypi.org/legacy/ dist/*