[#59] Add documentation build gate

This change introduces a job to build airshipctl documentation and
publish a preview for each new PS.

Related #59

Change-Id: I741c59f2c1dc50e66bf3cacfc8cb385ec9ec223d
Signed-off-by: Drew Walters <andrew.walters@att.com>

roles/airshipctl-build-docs/tasks/main.yaml

@@ -0,0 +1,16 @@
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+- name: Buid airshipctl Docs
+  shell: "make docs"
+  args:
+    chdir: "{{ zuul.project.src_dir }}"