Update the README.rst with accurate requirements

We no longer have a 'optional-requirements.txt' file
so the README.rst should not mention it existing (since
it's not there anymore) so this updates that file with
valid requirements and where they are located (and includes
examples of optional requirements with links to there
project pages).

Change-Id: Idb5fa3db8fc55027993b737cf251bd5257ab87be

1 files changed, 18 insertions, 11 deletions

diff --git a/README.rst b/README.rst
index a19bc4d..c5e1f10 100644
--- a/README.rst
+++ b/README.rst
@@ -21,16 +21,19 @@ Testing and requirements
 Requirements
 ~~~~~~~~~~~~
 
-Because TaskFlow has many optional (pluggable) parts like persistence
-backends and engines, we decided to split our requirements into two
-parts: - things that are absolutely required by TaskFlow (you can't use
-TaskFlow without them) are put into ``requirements-pyN.txt`` (``N`` being the
-Python *major* version number used to install the package); - things that are
-required by some optional part of TaskFlow (you can use TaskFlow without
-them) are put into ``optional-requirements.txt``; if you want to use the
-feature in question, you should add that requirements to your project or
-environment; - as usual, things that required only for running tests are
-put into ``test-requirements.txt``.
+Because this project has many optional (pluggable) parts like persistence
+backends and engines, we decided to split our requirements into three
+parts: - things that are absolutely required (you can't use the project
+without them) are put into ``requirements-pyN.txt`` (``N`` being the
+Python *major* version number used to install the package). The requirements
+that are required by some optional part of this project (you can use the
+project without them) are put into our ``tox.ini`` file (so that we can still
+test the optional functionality works as expected). If you want to use the
+feature in question (`eventlet`_ or the worker based engine that
+uses `kombu`_ or the `sqlalchemy`_ persistence backend or jobboards which
+have an implementation built using `kazoo`_ ...), you should add
+that requirement(s) to your project or environment; - as usual, things that
+required only for running tests are put into ``test-requirements.txt``.
 
 Tox.ini
 ~~~~~~~
@@ -51,5 +54,9 @@ We also have sphinx documentation in ``docs/source``.
 
     $ python setup.py build_sphinx
 
-.. _tox: http://testrun.org/tox/latest/
+.. _kazoo: http://kazoo.readthedocs.org/
+.. _sqlalchemy: http://www.sqlalchemy.org/
+.. _kombu: http://kombu.readthedocs.org/
+.. _eventlet: http://eventlet.net/
+.. _tox: http://tox.testrun.org/
 .. _developer documentation: http://docs.openstack.org/developer/taskflow/