Create RELEASE.rst

RELEASE.rst

@@ -63,6 +63,12 @@ Or multi version...
 
     pip install -U twine; (VERSION=`python setup.py --version`; rm -rf .release; mkdir .release; git archive `git rev-parse $VERSION` | tar xf - -C .release; cd .release/; for v in 3.5 3.6; do pip$v install -U wheel; python$v setup.py sdist bdist_egg bdist_wheel; done; twine upload dist/*-`python setup.py --version`*)
 
+And maybe, test that the release is now installable...
+
+.. code-block:: shell
+
+    (name=`python setup.py --name`; for v in 3.5 3.6; do python$v -m pip install -U virtualenv; python$v -m virtualenv -p python$v .rtest$v; cd .rtest$v; bin/pip install $name; bin/python -c "import $name; print($name.__name__, $name.__version__);"; cd ..; rm -rf .rtest$v; done; )
+
 5. (private) Build containers, push and patch kubernetes
 
 .. code-block:: shell