Disable tempest jobs for doc only changes

For doc only changes, there is no need to run tempest jobs which
require more time. This commit disables the tempest jobs if
doc only changes,
only unit-test changes

Closes-Bug:#1732829
Change-Id: Idc0604beff383f435705acfd55de57258a71332c

.zuul.yaml

@@ -1,6 +1,11 @@
 - job:
     name: congress-devstack-api-base
     parent: legacy-dsvm-base
+    irrelevant-files:
+      - ^.*\.rst$
+      - ^doc/.*$
+      - ^congress/tests/.*$
+      - ^releasenotes/.*$
     required-projects:
       - openstack-infra/devstack-gate
       - openstack/aodh
@@ -22,6 +27,11 @@
     parent: legacy-dsvm-base
     vars:
       database: mysql
+    irrelevant-files:
+      - ^.*\.rst$
+      - ^doc/.*$
+      - ^congress/tests/.*$
+      - ^releasenotes/.*$
     required-projects:
       - openstack-infra/devstack-gate
       - openstack/aodh
@@ -54,6 +64,11 @@
 - job:
     name: congress-devstack-py35-api-mysql
     parent: legacy-dsvm-base
+    irrelevant-files:
+      - ^.*\.rst$
+      - ^doc/.*$
+      - ^congress/tests/.*$
+      - ^releasenotes/.*$
     voting: false
     required-projects:
       - openstack-infra/devstack-gate