minor #12274 Reworded all the docs related to templates and Twig (javiereguiluz)

This PR was squashed before being merged into the 4.3 branch (closes #12274).

Discussion
----------

Reworded all the docs related to templates and Twig

As we did in the past with other topics, this pull request revamps the templating/templates/twig docs. The main goals were:

* Create a single article `/templates.rst` that explain everything about templates.
* Keep some `templating/*.rst` articles for uncommon things (PHP, Twig extensions, hinclude, etc.)
* Remove all the small `templating/*.rst` articles.
* Simplify all explanations and reduce verbosity.
* Add more cross-links between articles.

-----

The TOC of the new article looks like this:

```
Twig Templating Language
    Twig Configuration
Creating Templates
    Template Naming
    Template Location
    Template Variables
    Linking to Other Pages
    Linking to CSS and JavaScript Assets
    The App Global Variable
Rendering Templates
    Rendering Templates in Routes
    Rendering Templates in Controllers
    Rendering Templates in Services
    Rendering Templates in Emails
    Checking if a Template Exists
Debugging Templates
    Linting Twig Templates
    Inspecting Twig Information
    The Dump Twig Utilities
Reusing Template Contents
    Including Templates
    Embedding Controllers
    Template Inheritance and Layouts
Output Escaping
Template Namespaces
Learn More
```

Commits
-------

ec618e1 Reworded all the docs related to templates and Twig

Author: javiereguiluz

_build/redirection_map

@@ -446,3 +446,13 @@
 /form/action_method /forms
 /reference/requirements /setup
  /bundles/inheritance /bundles/override
+/templating /templates
+/templating/escaping /templates
+/templating/syntax /templates
+/templating/debug /templates
+/templating/render_without_controller /templates
+/templating/app_variable /templates
+/templating/formats /templates
+/templating/namespaced_paths /templates
+/templating/embedding_controllers /templates
+/templating/inheritance /templates

components/http_foundation.rst

@@ -57,6 +57,8 @@ which is almost equivalent to the more verbose, but also more flexible,
         $_SERVER
     );
 
+.. _accessing-request-data:
+
 Accessing Request Data
 ~~~~~~~~~~~~~~~~~~~~~~
 

components/templating.rst

@@ -28,8 +28,8 @@ Usage
 .. seealso::
 
     This article explains how to use the Templating features as an independent
-    component in any PHP application. Read the :doc:`/templating` article to
-    learn about how to work with templates in Symfony applications.
+    component in any PHP application. Read the article about :doc:`templates </templates>`
+    to learn about how to work with templates in Symfony applications.
 
 The :class:`Symfony\\Component\\Templating\\PhpEngine` class is the entry point
 of the component. It needs a
@@ -211,5 +211,5 @@ Learn More
     :glob:
 
     /components/templating/*
-    /templating
+    /templates
     /templating/*

configuration/front_controllers_and_kernel.rst

@@ -123,6 +123,8 @@ new kernel.
 .. index::
    single: Configuration; Debug mode
 
+.. _debug-mode:
+
 Debug Mode
 ~~~~~~~~~~
 

controller.rst

@@ -179,7 +179,7 @@ object for you::
     return $this->render('lucky/number.html.twig', ['number' => $number]);
 
 Templating and Twig are explained more in the
-:doc:`Creating and Using Templates article </templating>`.
+:doc:`Creating and Using Templates article </templates>`.
 
 .. index::
    single: Controller; Accessing services
@@ -461,7 +461,8 @@ and then redirects. The message key (``notice`` in this example) can be anything
 you'll use this key to retrieve the message.
 
 In the template of the next page (or even better, in your base layout template),
-read any flash messages from the session using ``app.flashes()``:
+read any flash messages from the session using the ``flashes()`` method provided
+by the :ref:`Twig global app variable <twig-app-variable>`:
 
 .. code-block:: html+twig
 
@@ -650,15 +651,15 @@ handle caching and more.
 Keep Going!
 -----------
 
-Next, learn all about :doc:`rendering templates with Twig </templating>`.
+Next, learn all about :doc:`rendering templates with Twig </templates>`.
 
 Learn more about Controllers
 ----------------------------
 
 .. toctree::
     :hidden:
 
-    templating
+    templates
 
 .. toctree::
     :maxdepth: 1

event_dispatcher.rst

@@ -206,9 +206,9 @@ Request Events, Checking Types
 ------------------------------
 
 A single page can make several requests (one master request, and then multiple
-sub-requests - typically by :doc:`/templating/embedding_controllers`). For the core
-Symfony events, you might need to check to see if the event is for a "master" request
-or a "sub request"::
+sub-requests - typically when :ref:`embedding controllers in templates <templates-embed-controllers>`).
+For the core Symfony events, you might need to check to see if the event is for
+a "master" request or a "sub request"::
 
     // src/EventListener/RequestListener.php
     namespace App\EventListener;

getting_started/index.rst

@@ -8,5 +8,5 @@ Getting Started
     /page_creation
     /routing
     /controller
-    /templating
+    /templates
     /configuration

http_cache/esi.rst

@@ -114,8 +114,8 @@ independently of the rest of the page::
 
 In this example, the full-page cache has a lifetime of ten minutes.
 Next, include the news ticker in the template by embedding an action.
-This is done via the ``render`` helper (see :doc:`/templating/embedding_controllers`
-for more details).
+This is done via the ``render()`` helper (for more details, see how to
+:ref:`embed controllers in templates <templates-embed-controllers>`).
 
 As the embedded content comes from another page (or controller for that
 matter), Symfony uses the standard ``render`` helper to configure ESI tags:

introduction/from_flat_php_to_symfony.rst

@@ -532,7 +532,7 @@ a simple application. Along the way, you've made a simple routing
 system and a method using ``ob_start()`` and ``ob_get_clean()`` to render
 templates. If, for some reason, you needed to continue building this "framework"
 from scratch, you could at least use Symfony's standalone
-:doc:`Routing </components/routing>` component and :doc:`Twig </templating>`,
+:doc:`Routing </components/routing>` component and :doc:`Twig </templates>`,
 which already solve these problems.
 
 Instead of re-solving common problems, you can let Symfony take care of

mailer.rst

@@ -291,7 +291,7 @@ create an event subscriber to set it automatically::
 Twig: HTML & CSS
 ----------------
 
-The Mime component integrates with the :doc:`Twig template engine </templating>`
+The Mime component integrates with the :ref:`Twig template engine <twig-language>`
 to provide advanced features such as CSS style inlining and support for HTML/CSS
 frameworks to create complex HTML email messages. First, make sure Twig is installed: