Update (git|review).openstack.org links to opendev

This updates links going to git.openstack.org and review.openstack.org
to go to their respective opendev locations to avoid redirects.

Change-Id: I78e3bb5303718962f591117f9c0ee11f2314b128
Closes-Bug: #1833256
diff --git a/doc/source/guides/single-vm.rst b/doc/source/guides/single-vm.rst
index 45b8f2d..8ebf2a6 100644
--- a/doc/source/guides/single-vm.rst
+++ b/doc/source/guides/single-vm.rst
@@ -60,7 +60,7 @@
             DEBIAN_FRONTEND=noninteractive sudo apt-get install -qqy git || sudo yum install -qy git
             sudo chown stack:stack /home/stack
             cd /home/stack
-            git clone https://git.openstack.org/openstack-dev/devstack
+            git clone https://opendev.org/openstack/devstack
             cd devstack
             echo '[[local|localrc]]' > local.conf
             echo ADMIN_PASSWORD=password >> local.conf