case PyPI correctly

Signed-off-by: Thomas Grainger <tom.grainger@procensus.com>

README.md

@@ -6,7 +6,7 @@ A Python library for the Docker Engine API. It lets you do anything the `docker`
 
 ## Installation
 
-The latest stable version [is available on PyPi](https://pypi.python.org/pypi/docker/). Either add `docker` to your `requirements.txt` file or install with pip:
+The latest stable version [is available on PyPI](https://pypi.python.org/pypi/docker/). Either add `docker` to your `requirements.txt` file or install with pip:
 
     pip install docker
 

docs/index.rst

@@ -8,7 +8,7 @@ For more information about the Remote API, `see its documentation <https://docs.
 Installation
 ------------
 
-The latest stable version `is available on PyPi <https://pypi.python.org/pypi/docker/>`_. Either add ``docker`` to your ``requirements.txt`` file or install with pip::
+The latest stable version `is available on PyPI <https://pypi.python.org/pypi/docker/>`_. Either add ``docker`` to your ``requirements.txt`` file or install with pip::
 
     pip install docker