minor symfony#7873 Reworded the introduction of the contributing docs (javiereguiluz)

This PR was squashed before being merged into the 2.7 branch (closes symfony#7873).

Discussion
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Reworded the introduction of the contributing docs

I propose a more gentle and actionable introduction to the "contributing docs" guide. The current introduction is confusing and intimidating to newcomers:

![contributing-index](https://cloud.githubusercontent.com/assets/73419/25700725/3afaea3e-30c9-11e7-8237-2734986ab93a.png)

Commits
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6e23024 Reworded the introduction of the contributing docs

Author: xabbuh

contributing/documentation/format.rst

@@ -1,8 +1,8 @@
 Documentation Format
 ====================
 
-The Symfony documentation uses reStructuredText_ as its markup language and
-Sphinx_ for generating the documentation in the formats read by the end users,
+The Symfony documentation uses `reStructuredText`_ as its markup language and
+`Sphinx`_ for generating the documentation in the formats read by the end users,
 such as HTML and PDF.
 
 reStructuredText

contributing/documentation/index.rst

@@ -1,13 +1,25 @@
 Contributing Documentation
 ==========================
 
-.. toctree::
-    :maxdepth: 2
+These short articles explain everything you need to contribute to the Symfony
+documentation:
+
+:doc:`The Contribution Process </contributing/documentation/overview>`
+  Explains the steps to follow to contribute fixes and new contents. It's the
+  same contribution process followed by most open source projects, so you may
+  already know everything that is needed.
+
+:doc:`Documentation Formats </contributing/documentation/format>`
+  Explains the technical details of the reStructuredText format that is used to
+  write the docs. Skip it if you are already familiar with this format.
+
+:doc:`Documentation Standards </contributing/documentation/standards>`
+  Explains how to write docs and code examples to match the style and tone of
+  the rest of the existing documentation.
 
-    overview
-    format
-    standards
-    license
+:doc:`License </contributing/documentation/license>`
+  Explains the details of the Creative Commons BY-SA 3.0 license used for the
+  Symfony Documentation.
 
 .. toctree::
     :hidden:

contributing/documentation/overview.rst

@@ -1,30 +1,16 @@
 Contributing to the Documentation
 =================================
 
-One of the essential principles of the Symfony project is that **documentation
-is as important as code**. That's why a great amount of resources are dedicated
-to documenting new features and to keeping the rest of the documentation
-up-to-date.
-
-More than 1,000 developers all around the world have contributed to Symfony's
-documentation and we are glad that you are considering joining this big family.
-This guide will explain everything you need to contribute to the Symfony
-documentation.
-
 Before Your First Contribution
 ------------------------------
 
-**Before contributing**, you should consider the following:
-
-* Symfony documentation is written using `reStructuredText`_ markup language.
-  If you are not familiar with this format, read
-  :doc:`this article </contributing/documentation/format>` for a quick overview
-  of its basic features.
-* Symfony documentation is hosted on `GitHub`_. You'll need a free GitHub user
-  account to contribute to the documentation.
-* Symfony documentation is published under a
-  :doc:`Creative Commons BY-SA 3.0 License </contributing/documentation/license>`
-  and all your contributions will implicitly adhere to that license.
+**Before contributing**, you need to:
+
+* Sign up for a free `GitHub`_ account, which is the service where the Symfony
+  documentation is hosted.
+* Be familiar with the `reStructuredText`_ markup language, which is used to
+  write Symfony docs. Read :doc:`this article </contributing/documentation/format>`
+  for a quick overview.
 
 .. _minor-changes-e-g-typos:
 

contributing/documentation/standards.rst

@@ -1,8 +1,8 @@
 Documentation Standards
 =======================
 
-In order to help the reader as much as possible and to create code examples that
-look and feel familiar, you should follow these standards.
+Contributions must follow these standards to match the style and tone of the
+rest of the Symfony documentation.
 
 Sphinx
 ------

contributing/documentation/translations.rst

@@ -1,7 +1,7 @@
 Translations
 ============
 
-The Symfony documentation is not officially translated, though some community
-groups still maintain some translations. For more information, see `this blog post`_.
+The official Symfony documentation is published only in English, but some
+community groups maintain `unofficial translations`_.
 
-.. _`this blog post`: https://symfony.com/blog/discontinuing-the-symfony-community-translations
+.. _`unofficial translations`: https://symfony.com/blog/discontinuing-the-symfony-community-translations