Fix pip download example in usage
@@ -493,10 +493,10 @@ to PyPI.
First, download the archives that fulfill your requirements::
-$ pip install --download DIR -r requirements.txt
+$ pip download DIR -r requirements.txt
-Note that ``pip install --download`` will look in your wheel cache first, before
+Note that ``pip download`` will look in your wheel cache first, before
trying to download from PyPI. If you've never installed your requirements
before, you won't have a wheel cache for those items. In that case, if some of
your requirements don't come as wheels from PyPI, and you want wheels, then run
