update changelog for the null-coalesce operator
update changelog for the null-coalesce operator

nicolas-grekas/symfony,nicolas-grekas/symfony,symfony/symfony,symfony/symfony,derrabus/symfony,nicolas-grekas/symfony,HeahDude/symfony,derrabus/symfony,HeahDude/symfony,symfony/symfony,derrabus/symfony,HeahDude/symfony,derrabus/symfony,nicolas-grekas/symfony,HeahDude/symfony,symfony/symfony