[ussuri][goal] Update contributor documentation

This patch updates/adds the contributor documentation to follow
the guidelines of the Ussuri cycle community goal[1].

[1] https://governance.openstack.org/tc/goals/selected/ussuri/project-ptl-and-contrib-docs.html
Story: #2007236
Task: #38554

Change-Id: Ib54b16543eb428087555cd3411bae51244d1aa65
diff --git a/CONTRIBUTING.rst b/CONTRIBUTING.rst
index a89ad94..2300763 100644
--- a/CONTRIBUTING.rst
+++ b/CONTRIBUTING.rst
@@ -1,17 +1,19 @@
-If you would like to contribute to the development of OpenStack, you must
-follow the steps in this page:
+The source repository for this project can be found at:
 
-   https://docs.openstack.org/infra/manual/developers.html
+   https://opendev.org/openstack/tempest
 
-If you already have a good understanding of how the system works and your
-OpenStack accounts are set up, you can skip to the development workflow
-section of this documentation to learn how changes to OpenStack should be
-submitted for review via the Gerrit tool:
+Pull requests submitted through GitHub are not monitored.
 
-   https://docs.openstack.org/infra/manual/developers.html#development-workflow
+To start contributing to OpenStack, follow the steps in the contribution guide
+to set up and use Gerrit:
 
-Pull requests submitted through GitHub will be ignored.
+   https://docs.openstack.org/contributors/code-and-documentation/quick-start.html
 
-Bugs should be filed on Launchpad, not GitHub:
+Bugs should be filed on Launchpad:
 
    https://bugs.launchpad.net/tempest
+
+For more specific information about contributing to this repository, see the
+Tempest contributor guide:
+
+   https://docs.openstack.org/tempest/latest/contributor/contributing.html