Fix some rst weirdness in the uage docs
MODIFY
docs/source/usage.rst
docs/source/usage.rst
@@ -26,9 +26,9 @@ For example, use the following to build an image of the
jupyter-repo2docker https://github.com/jakevdp/PythonDataScienceHandbook
To build a particular branch and commit, use the argument ``--ref`` to
-specify the ``branch-name/commit-hash``::
+specify the ``branch-name`` or ``commit-hash``::
- jupyter-repo2docker https://github.com/jakevdp/PythonDataScienceHandbook --ref master/599aa0fe3f882c0001670e676e5a8d43b92c35fc
+ jupyter-repo2docker https://github.com/jakevdp/PythonDataScienceHandbook --ref 599aa0fe3f882c0001670e676e5a8d43b92c35fc
.. tip::
For reproducibile research, we recommend specifying a commit-hash to

Fix some rst weirdness in the uage docs