Documented true regex

Author: wouterj

components/console/helpers/questionhelper.rst

@@ -41,6 +41,24 @@ The second argument to
 is the default value to return if the user doesn't enter any input. Any other
 input will ask the same question again.
 
+.. tip::
+
+    You can customize the regex used to check if the answer means "yes" in the
+    third argument of the constructor. For instance, to allow anything that
+    starts with either ``y`` or ``j``, you would set it to::
+
+        $question = new ConfirmationQuestion(
+            'Continue with this action?',
+            false,
+            '/^(y|j)/i'
+        );
+
+    The regex defaults to ``/^y/i``.
+
+    .. versionadded:: 2.7
+        The regex argument was introduced in Symfony 2.7, before only answers
+        starting with ``y`` were considered as yes.
+
 Asking the User for Information
 -------------------------------