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/doc/source/plugin.rst b/doc/source/plugin.rst
index dc0e94c..a9e2059 100644
--- a/doc/source/plugin.rst
+++ b/doc/source/plugin.rst
@@ -43,7 +43,7 @@
 In order to create the basic structure with base classes and test directories
 you can use the tempest-plugin-cookiecutter project::
 
-  > pip install -U cookiecutter && cookiecutter https://git.openstack.org/openstack/tempest-plugin-cookiecutter
+  > pip install -U cookiecutter && cookiecutter https://opendev.org/openstack/tempest-plugin-cookiecutter
 
   Cloning into 'tempest-plugin-cookiecutter'...
   remote: Counting objects: 17, done.