Merge branch '4.2'

* 4.2:
  Update requirements.rst
  Added SymfonyCloud to the list of deployment services
  Removed an unneeded article
  Create a "Clever cloud" deployment section

Author: javiereguiluz

deployment.rst

@@ -66,10 +66,12 @@ Using Platforms as a Service
 Using a Platform as a Service (PaaS) can be a great way to deploy your Symfony app
 quickly and easily. There are many PaaS - below are a few that work well with Symfony:
 
+* `Symfony Cloud`_
 * `Heroku`_
 * `Platform.sh`_
 * `Azure`_
 * `fortrabbit`_
+* `Clever Cloud`_
 
 Using Build Scripts and other Tools
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -264,3 +266,5 @@ Learn More
 .. _`Azure`: https://azure.microsoft.com/en-us/develop/php/
 .. _`fortrabbit`: https://help.fortrabbit.com/install-symfony
 .. _`EasyDeployBundle`: https://github.com/EasyCorp/easy-deploy-bundle
+.. _`Clever Cloud`: https://www.clever-cloud.com/doc/php/tutorial-symfony/
+.. _`Symfony Cloud`: https://symfony.com/doc/master/cloud/intro.html

reference/requirements.rst

@@ -6,16 +6,41 @@
 Requirements for Running Symfony
 ================================
 
-Symfony 4 requires **PHP 7.1.3** or higher to run, in addition to other minor
-requirements. To make things simple, Symfony provides a tool to quickly check if
-your system meets all those requirements. Run this command to install the tool:
+These are the technical requirements to run Symfony 4 applications:
+
+* **PHP version**: 7.1.3 or higher
+* **PHP extensions**: (all of them are installed and enabled by default in PHP 7+)
+
+  * `Ctype`_
+  * `iconv`_
+  * `JSON`_
+  * `PCRE`_
+  * `Session`_
+  * `SimpleXML`_
+  * `Tokenizer`_
+
+* **Writable directories**: (must be writable by the web server)
+
+  * The project's cache directory (``var/cache/`` by default, but the app can
+    :ref:`override the cache dir <override-cache-dir>`)
+  * The project's log directory (``var/log/`` by default, but the app can
+    :ref:`override the logs dir <override-logs-dir>`)
+
+Checking Requirements Automatically
+-----------------------------------
+
+To make things simple, Symfony provides a tool to quickly check if your system
+meets these requirements. In addition, the tool provides recommendations if
+applicable.
+
+Run this command to install the tool:
 
 .. code-block:: terminal
 
     $ cd your-project/
     $ composer require symfony/requirements-checker
 
-Beware that PHP can define a different configuration for the command console and
+Beware that PHP may use different configurations for the command console and
 the web server, so you need to check requirements in both environments.
 
 Checking Requirements for the Web Server
@@ -38,4 +63,12 @@ Checking Requirements for the Command Console
 
 The requirements checker tool adds a script to your Composer configuration to
 check the requirements automatically. There's no need to execute any command; if
-there is any issue, you'll see them in the console output.
+there are any issues, you'll see them in the console output.
+
+.. _`iconv`: https://php.net/book.iconv
+.. _`JSON`: https://php.net/book.json
+.. _`Session`: https://php.net/book.session
+.. _`Ctype`: https://php.net/book.ctype
+.. _`Tokenizer`: https://php.net/book.tokenizer
+.. _`SimpleXML`: https://php.net/book.simplexml
+.. _`PCRE`: https://php.net/book.pcre