Update the old doc links

Update the old url links in docs.

Change-Id: Iad72842a7a22c820c703a9270af8ce8ad2dd25ff
diff --git a/CONTRIBUTING.rst b/CONTRIBUTING.rst
index 0ebda35..217f5de 100644
--- a/CONTRIBUTING.rst
+++ b/CONTRIBUTING.rst
@@ -1,14 +1,14 @@
 If you would like to contribute to the development of OpenStack, you must
 follow the steps in this page:
 
-   http://docs.openstack.org/infra/manual/developers.html
+   https://docs.openstack.org/infra/manual/developers.html
 
 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:
 
-   http://docs.openstack.org/infra/manual/developers.html#development-workflow
+   https://docs.openstack.org/infra/manual/developers.html#development-workflow
 
 Pull requests submitted through GitHub will be ignored.