minor #11741 Adding "special case" when need to select development branch instead of master for new features. (oleg-andreyev)

This PR was merged into the 3.4 branch.

Discussion
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Adding "special case" when need to select development branch instead of master for new features.

As per discussion in #11457 and symfony/symfony#31177 (comment) updated section on how to select branch

Commits
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1c2bae2 added "special case"

Author: javiereguiluz

contributing/code/pull_requests.rst

@@ -131,6 +131,13 @@ work:
 
 * ``master``, if you are adding a new feature.
 
+.. note::
+
+    A new **Symfony major version** (e.g. 3.0, 4.0) comes out every *two years*.
+    It is a very special case when new features must go to development branch.
+
+    Check `Symfony Roadmap`_ for latest development branch and not to ``master``
+
 .. note::
 
     All bug fixes merged into maintenance branches are also merged into more
@@ -423,3 +430,4 @@ before merging.
 .. _`Symfony Slack`: https://symfony.com/slack-invite
 .. _`Travis-CI`: https://travis-ci.org/symfony/symfony
 .. _`draft status`: https://help.github.com/en/articles/about-pull-requests#draft-pull-requests
+.. _`Symfony Roadmap`: https://symfony.com/roadmap