minor #8995 Mention that PSR-1 doesn't recommend CamelCase or anything else (javiereguiluz)

This PR was squashed before being merged into the 2.7 branch (closes #8995).

Discussion
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Mention that PSR-1 doesn't recommend CamelCase or anything else

This fixes #8991.

Commits
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8ad93aa Mention that PSR-1 doesn't recommend CamelCase or anything else

Author: javiereguiluz

components/serializer.rst

@@ -421,8 +421,9 @@ CamelCase to snake_case
     interface was introduced in Symfony 2.7.
 
 In many formats, it's common to use underscores to separate words (also known
-as snake_case). However, PSR-1 specifies that the preferred style for PHP
-properties and methods is CamelCase.
+as snake_case). However, in Symfony applications is common to use CamelCase to
+name properties (even though the `PSR-1 standard`_ doesn't recommend any
+specific case for property names).
 
 Symfony provides a built-in name converter designed to transform between
 snake_case and CamelCased styles during serialization and deserialization
@@ -646,5 +647,6 @@ Learn more
     A popular alternative to the Symfony Serializer Component is the third-party
     library, `JMS serializer`_ (released under the Apache license, so incompatible with GPLv2 projects).
 
+.. _`PSR-1 standard`: http://www.php-fig.org/psr/psr-1/
 .. _`JMS serializer`: https://github.com/schmittjoh/serializer
 .. _Packagist: https://packagist.org/packages/symfony/serializer