Merge branch '2.6' into 2.7

* 2.6:
  Document Platform.sh on the contributing section.
  Mention Platform.sh on README.
  Better Sphinx version.
  Improve configuration files.
  Prepare Platform.sh configuration files.

.platform.app.yaml

@@ -0,0 +1,55 @@
+# This file describes an application. You can have multiple applications
+# in the same project.
+
+# The name of this app. Must be unique within a project.
+name: symfonydocs
+
+# The toolstack used to build the application.
+type: "php"
+
+build:
+    flavor: "composer"
+
+# The configuration of app when it is exposed to the web.
+web:
+    # The public directory of the app, relative to its root.
+    document_root: "/_build/html"
+    index_files:
+      - index.html
+    whitelist:
+      - \.html$
+      - \.txt$
+
+      # CSS and Javascript.
+      - \.css$
+      - \.js$
+      - \.hbs$
+
+      # image/* types.
+      - \.gif$
+      - \.png$
+      - \.ico$
+      - \.svgz?$
+
+      # fonts types.
+      - \.ttf$
+      - \.eot$
+      - \.woff$
+      - \.otf$
+
+      # robots.txt.
+      - /robots\.txt$
+
+# The size of the persistent disk of the application (in MB).
+disk: 512
+
+# Build time dependencies.
+dependencies:
+  python:
+    sphinx: ">=1"
+
+# The hooks that will be performed when the package is deployed.
+hooks:
+    build: |
+      pip install git+https://github.com/fabpot/sphinx-php.git
+      make html

.platform/routes.yaml

@@ -0,0 +1,16 @@
+http://www.{default}/:
+  to: http://{default}/
+  type: redirect
+http://{default}/:
+  cache:
+    cookies:
+    - '*'
+    default_ttl: 0
+    enabled: true
+    headers:
+    - Accept
+    - Accept-Language
+  ssi:
+    enabled: false
+  type: upstream
+  upstream: symfonydocs:php

.platform/services.yaml

@@ -0,0 +1 @@
+# Keeping this file empty to not deploy unused services.

README.markdown

@@ -14,3 +14,8 @@ Contributing
 We love contributors! For more information on how you can contribute to the
 Symfony documentation, please read
 [Contributing to the Documentation](https://symfony.com/doc/current/contributing/documentation/overview.html)
+
+Platform.sh
+-----------
+
+Pull requests are automatically built by [Platform.sh](https://platform.sh).

contributing/documentation/overview.rst

@@ -248,6 +248,27 @@ steps to contribute to the Symfony documentation, which you can use as a
 
 You guessed right: after all this hard work, it's **time to celebrate again!**
 
+
+Review your changes
+-------------------
+
+Every GitHub Pull Request is automatically built and deployed by `Platform.sh`_
+on a single environment that you can access on your browser to review your 
+changes.
+
+.. image:: /images/contributing/docs-pull-request-platformsh.png
+   :align: center
+   :alt:   Platform.sh Pull Request Deployment
+
+To access the `Platform.sh`_ environment URL, simply go to your Pull Request 
+page on GitHub and click on ``Details``.
+
+.. note::
+
+    The specific configuration files at the root of the Git repository: 
+    ``.platform.app.yaml``, ``.platform/services.yaml`` and 
+    ``.platform/routes.yaml`` allow `Platform.sh`_ to build Pull Requests.
+
 Minor Changes (e.g. Typos)
 --------------------------
 
@@ -324,3 +345,4 @@ definitely don't want you to waste your time!
 .. _SensioLabsConnect: https://connect.sensiolabs.com/
 .. _`Symfony Documentation Badge`: https://connect.sensiolabs.com/badge/36/symfony-documentation-contributor
 .. _`sync your fork`: https://help.github.com/articles/syncing-a-fork
+.. _`Platform.sh`: https://platform.sh