feature #5543 Add deprecation notice to "choice_list" option of ChoiceType (XitasoChris)

This PR was squashed before being merged into the 2.7 branch (closes #5543).

Discussion
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Add deprecation notice to "choice_list" option of ChoiceType

Per https://github.com/symfony/symfony/blob/2.8/UPGRADE-2.7.md the choice_list option of ChoiceType is deprecated as of Symfony 2.7. It is recommended to use choices or choice_loader, however the latter does not have a documentation entry yet.

Commits
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a4db275 Add deprecation notice to "choice_list" option of ChoiceType

Author: wouterj

reference/forms/types/choice.rst

@@ -102,6 +102,11 @@ is the item value and the array value is the item's label::
 choice_list
 ~~~~~~~~~~~
 
+.. caution::
+
+    The ``choice_list`` option of ChoiceType was deprecated in Symfony 2.7.
+    You should use ``choices`` or ``choice_loader`` now.
+
 **type**: :class:`Symfony\\Component\\Form\\Extension\\Core\\ChoiceList\\ChoiceListInterface`
 
 This is one way of specifying the options to be used for this field.