Fix 'ref' format errors in README file

While releasing new version in pypi, it perform the
validation on the package and give error if there is any
formatting issue.

README file is being used to upload on pypi and so validation
check fails[1] on current README due to 'ref' used for internal
doc link. Those links would not be available for outside the built doc.
This can be checked locally by:
    python setup.py check -s -r

This commit fixes those format issue by removing the ref and provide the
external links.

Change-Id: I678e792eaf4e362f48864da761461c7779a09155
diff --git a/README.rst b/README.rst
index 2028536..fdcbc6b 100644
--- a/README.rst
+++ b/README.rst
@@ -36,7 +36,7 @@
 Design Principles
 -----------------
 
-As a `Tempest plugin`_, Patrole borrows some `design principles`_ from Tempest,
+As a `Tempest plugin`_, Patrole borrows some design principles from `Tempest design principles`_,
 but not all, as its testing scope is confined to policies.
 
 * *Stability*. Patrole uses OpenStack public interfaces. Tests in Patrole
@@ -76,7 +76,7 @@
 * *Self-testing*. Patrole should be self-testing.
 
 .. _Tempest plugin: https://docs.openstack.org/tempest/latest/plugin.html
-.. _design principles: https://docs.openstack.org/tempest/latest/overview.html#design-principles
+.. _Tempest design principles: https://docs.openstack.org/tempest/latest/overview.html#design-principles
 .. _policy in code: https://specs.openstack.org/openstack/oslo-specs/specs/newton/policy-in-code.html
 .. _Nova repository: https://github.com/openstack/nova/tree/master/nova/policies
 .. _Keystone repository: https://github.com/openstack/keystone/tree/master/keystone/common/policies
@@ -120,7 +120,7 @@
 Quickstart
 ----------
 To run Patrole, you must first have `Tempest`_ installed and configured
-properly. Please reference Tempest's `Quickstart`_ guide to do so. Follow all
+properly. Please reference `Tempest_quickstart`_ guide to do so. Follow all
 the steps outlined therein. Afterward, proceed with the steps below.
 
 #. You first need to install Patrole. This is done with pip after you check out
@@ -139,7 +139,7 @@
 
 #. Next you must properly configure Patrole, which is relatively
    straightforward. For details on configuring Patrole refer to the
-   :ref:`patrole-configuration`.
+   `Patrole Configuration <https://docs.openstack.org/patrole/latest/configuration.html#patrole-configuration>`_.
 
 #. Once the configuration is done you're now ready to run Patrole. This can
    be done using the `tempest_run`_ command. This can be done by running::
@@ -170,14 +170,14 @@
 
 #. Log information from tests is captured in ``tempest.log`` under the Tempest
    repository. Some Patrole debugging information is captured in that log
-   related to expected test results and :ref:`role-overriding`.
+   related to expected test results and `Role Overriding <https://docs.openstack.org/patrole/latest/framework/rbac_utils.html#role-overriding>`_.
 
    More detailed RBAC testing log output is emitted to ``patrole.log`` under
    the Patrole repository. To configure Patrole's logging, see the
-   :ref:`patrole-configuration` guide.
+   `Patrole Configuration Guide <https://docs.openstack.org/patrole/latest/configuration.html#patrole-configuration>`_.
 
 .. _Tempest: https://github.com/openstack/tempest
-.. _Quickstart: https://docs.openstack.org/tempest/latest/overview.html#quickstart
+.. _Tempest_quickstart: https://docs.openstack.org/tempest/latest/overview.html#quickstart
 .. _tempest_run: https://docs.openstack.org/tempest/latest/run.html
 .. _testr: https://testrepository.readthedocs.org/en/latest/MANUAL.html
 .. _ostestr: https://docs.openstack.org/os-testr/latest/