Add wiki Admin guide and Contributing notes link to README

Change-Id: Iafb8e7b6fb483327a7baf95e9e273662b8918c56

README.rst

@@ -16,10 +16,13 @@ for deploying and managing containers as first class resources in OpenStack.
 
 For more information, please refer to the following resources:
 
-* **Free software:** under the `Apache license <http://www.apache.org/licenses/LICENSE-2.0>`_
+* **Free software:** under the `Apache license <http://www.apache.org/licenses/LICENSE-2.0>`
+* **Wiki:** https://wiki.openstack.org/wiki/Magnum_
 * **Documentation:** https://docs.openstack.org/magnum/latest/
+* **Admin guide:** https://docs.openstack.org/magnum/latest/admin/index.html
 * **Source:** https://opendev.org/openstack/magnum
 * **Blueprints:** https://blueprints.launchpad.net/magnum
 * **Bugs:** https://storyboard.openstack.org/#!/project/openstack/magnum
 * **REST Client:** https://opendev.org/openstack/python-magnumclient
 * **Release notes:** https://docs.openstack.org/releasenotes/magnum/index.html
+* **Contributing:** https://docs.openstack.org/magnum/latest/contributor/index.html