Replace git.openstack.org URLs with opendev.org URLs

Thorough replacement of git.openstack.org and review.openstack.org URLs
with their opendev.org counterparts.

Change-Id: I88e894db7b854d32593c770f5aa9b8a91fad7866
diff --git a/README.rst b/README.rst
index 73930f1..e8206ee 100644
--- a/README.rst
+++ b/README.rst
@@ -61,7 +61,7 @@
 #. You first need to install Tempest. This is done with pip after you check out
    the Tempest repo::
 
-    $ git clone https://git.openstack.org/openstack/tempest
+    $ git clone https://opendev.org/openstack/tempest
     $ pip install tempest/
 
    This can be done within a venv, but the assumption for this guide is that