Add zuul jobs

Depends-On: I894d9875048cb000765b4c8d6d94f62cb02c2988
Depends-On: Ia68b6e7252a2c971d059962b8302661e272ec24d
Change-Id: I98c9e0c8c8b257bfd46c2e056dd44181bef9efad
Story: #2003734
Task: #26400
Signed-off-by: Trinh Nguyen <dangtrinhnt@gmail.com>

.zuul.yaml

@@ -0,0 +1,14 @@
+- project:
+    templates:
+      - openstack-python-jobs
+      - openstack-python35-jobs
+      - openstack-python36-jobs
+      - check-requirements
+      - openstack-lower-constraints-jobs
+      - build-openstack-docs-pti
+    check:
+      jobs:
+        - build-openstack-releasenotes
+    gate:
+      jobs:
+        - build-openstack-releasenotes