Add build-placement-api-ref

First step in converting legacy-api-ref job to v3 format: Adding a new
job.

Sync file list with the api-ref and api-guide jobs.

Needed-By: I6c57d43b464a26eb396f3c12d5a14b6b21fa2ef8
Change-Id: Ib50a094db845f63d802c0f76f4a9d44517f401fa

playbooks/build-placement-api-ref/post.yaml

@@ -0,0 +1,5 @@
+- hosts: all
+  roles:
+    - role: fetch-tox-output
+    - role: fetch-sphinx-output
+      sphinx_output_src: "{{ zuul.project.src_dir }}/placement-api-ref/build/html"

zuul.d/jobs.yaml

@@ -451,6 +451,8 @@
       - ^tox.ini$
       - ^api-ref/.*
       - ^doc/api_samples/.*
+      - bindep.txt
+      - other-requirements.txt
 
 - job:
     name: build-openstack-api-guide
@@ -469,6 +471,8 @@
     files:
       - ^tox.ini$
       - ^api-guide/.*
+      - bindep.txt
+      - other-requirements.txt
 
 - job:
     name: build-openstack-deploy-guide
@@ -486,6 +490,25 @@
       - bindep.txt
       - other-requirements.txt
 
+- job:
+    name: build-placement-api-ref
+    parent: openstack-tox
+    description: |
+      Build placement-api-ref document. This job runs only on master branch.
+    success-url: html/
+    post-run: playbooks/build-placement-api-ref/post
+    timeout: 1800
+    # We only publish the master branch, so no need to run
+    # for changes on other branches.
+    branches: master
+    vars:
+      tox_envlist: placement-api-ref
+    files:
+      - ^tox.ini$
+      - ^placement-api-ref/.*
+      - bindep.txt
+      - other-requirements.txt
+
 - job:
     name: legacy-base
     description: |