Reminder for OSX users not to use SUDO

Useful for those who haven't made it to the examples page yet. https://github.com/chadoh/docker/commit/dad4a998dc716e506c874ce0e792989b9df28748

Docker-DCO-1.1-Signed-off-by: No Ducks <onemannoducks@gmail.com> (github: noducks)

docs/sources/use/basics.rst

@@ -40,6 +40,8 @@ Repository to a local image cache.
    short form of the image ID. These short image IDs are the first 12
    characters of the full image ID - which can be found using ``docker
    inspect`` or ``docker images --no-trunc=true``
+   
+   **If you're using OS X** then you shouldn't use ``sudo``
 
 Running an interactive shell
 ----------------------------