minor #5817 fix version for entry_options and entry_type (craue)

This PR was merged into the 2.8 branch.

Discussion
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fix version for `entry_options` and `entry_type`

#5051 was merged into 2.8, not 2.7.

Commits
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dc5a831 fixed version for `entry_options` and `entry_type`

reference/forms/types/collection.rst

@@ -276,9 +276,9 @@ the empty values will be kept.
 entry_options
 ~~~~~~~~~~~~~
 
-.. versionadded:: 2.7
-    The ``entry_options`` option was introduced in Symfony 2.7 in favor of
-    ``options``, which is available prior to 2.7.
+.. versionadded:: 2.8
+    The ``entry_options`` option was introduced in Symfony 2.8 in favor of
+    ``options``, which is available prior to 2.8.
 
 **type**: ``array`` **default**: ``array()``
 
@@ -303,9 +303,9 @@ type::
 entry_type
 ~~~~~~~~~~
 
-.. versionadded:: 2.7
-    The ``entry_type`` option was introduced in Symfony 2.7 in favor of
-    ``type``, which is available prior to 2.7.
+.. versionadded:: 2.8
+    The ``entry_type`` option was introduced in Symfony 2.8 in favor of
+    ``type``, which is available prior to 2.8.
 
 **type**: ``string`` or :class:`Symfony\\Component\\Form\\FormTypeInterface` **required**