Update HDFS docs to fix some wording issues (mlflow#1147)

docs/source/tracking.rst

@@ -371,28 +371,28 @@ the client in order to enforce this property.
 
 
 HDFS
-^^^^^
+^^^^
 
-To store artifacts in an HDFS, specify a URI of the form ``hdfs://<path>``. It can contain host and port:
+To store artifacts in HDFS, specify a ``hdfs:`` URI. It can contain host and port:
 
 |     ``hdfs://<host>:<port>/<path>`` or just the path:
 |     ``hdfs://<path>``
 |
 
-Choice is dependant on the authorization in use. Supported are two cases:
+There are also two ways to authenticate to HDFS:
 
-- Use current account authorization (Linux account)
+- Use current UNIX account authorization
 - Kerberos credentials using following environment variables:
 
 .. code-block:: bash
 
   export MLFLOW_KERBEROS_TICKET_CACHE=/tmp/krb5cc_22222222
   export MLFLOW_KERBEROS_USER=user_name_to_use
 
-Most of the cluster contest settings is read from ```hdfs-site.xml``` accessed by the hdfs native driver
+Most of the cluster contest settings is read from ```hdfs-site.xml``` accessed by the HDFS native driver
 driver using the ``CLASSPATH`` environment variable.
 
-Optionally one can select different version of native driver by:
+Optionally one can select a different version of the HDFS driver library using:
 
 .. code-block:: bash