Add release notes

Author: youtux

CHANGES.rst

@@ -4,8 +4,11 @@ Changelog
 Unreleased
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-- Drop support for pytest < 3.3.2
-- Step definitions generated by `pytest-bdd generate` will now `raise NotImplementedError` by default.
+- Drop support for pytest < 3.3.2.
+- Step definitions generated by ``$ pytest-bdd generate`` will now raise ``NotImplementedError`` by default.
+- ``@given(...)`` no longer accepts regex objects. It was deprecated long ago.
+- Improve project testing by treating warnings as exceptions.
+- ``pytest_bdd_step_validation_error`` will now always receive ``step_func_args`` as defined in the signature.
 
 3.0.2
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