Update Pegleg docs jobs

This patch brings Pegleg in line with other Airship projects in their
method of updating documentation.  This is achieved by:
1. Adding docs-on-readthedocs job
2. Adding readthedocs webhook and project name vars used for Pegleg
3. Removing airship-pegleg-doc-build
4. Removing doc-build playbook

Change-Id: Iaa4139ccb1cd9d7ca20a6b502ef2a152908147d0

.zuul.yaml

@@ -12,20 +12,22 @@
 
 - project:
     templates:
+      - docs-on-readthedocs
       - openstack-python36-jobs
       - openstack-python37-jobs
       - openstack-cover-jobs
       - release-notes-jobs-python3
+    vars:
+      rtd_webhook_id: '38574'
+      rtd_project_name: 'airship-pegleg'
     check:
       jobs:
         - openstack-tox-pep8
-        - airship-pegleg-doc-build
         - airship-pegleg-docker-build-gate-ubuntu
         - airship-pegleg-docker-build-gate-opensuse
     gate:
       jobs:
         - openstack-tox-pep8
-        - airship-pegleg-doc-build
         - airship-pegleg-docker-build-gate-ubuntu
         - airship-pegleg-docker-build-gate-opensuse
     post:
@@ -39,17 +41,6 @@
       - name: primary
         label: ubuntu-xenial
 
-- job:
-    name: airship-pegleg-doc-build
-    description: |
-      Locally build the documentation to check for errors
-    run: tools/gate/playbooks/doc-build.yaml
-    timeout: 300
-    nodeset: airship-pegleg-single-node
-    irrelevant-files:
-      - ^tests/.*$
-      - ^setup.cfg$
-
 - job:
     name: airship-pegleg-docker-build-gate-ubuntu
     timeout: 1800

tools/gate/playbooks/doc-build.yaml

@@ -1,20 +0,0 @@
-# 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.
-
-- hosts: primary
-  tasks:
-    - name: Build documents locally
-      make:
-        chdir: "{{ zuul.project.src_dir }}"
-        target: docs
-      register: result
-      failed_when: result.failed