Merge branch '4.4' into 5.0

* 4.4:
  Fix typo in the markup

Author: javiereguiluz

contributing/code/bc.rst

@@ -32,7 +32,7 @@ The second section, "Working on Symfony Code", is targeted at Symfony
 contributors. This section lists detailed rules that every contributor needs to
 follow to ensure smooth upgrades for our users.
 
-.. warning::
+.. caution::
 
     :doc:`Experimental Features </contributing/code/experimental>` and code
     marked with the ``@internal`` tags are excluded from our Backward

mailer.rst

@@ -27,7 +27,7 @@ can deliver emails over ``smtp`` by configuring your ``.env`` file (the
     # .env
     MAILER_DSN=smtp://user:pass@smtp.example.com:port
 
-.. warning::
+.. caution::
 
     If you are migrating from Swiftmailer (and the Swiftmailer bundle), be
     warned that the DSN format is different.