minor #10619 [Console] Remove invalid note about empty input options (chalasr)

This PR was merged into the 3.4 branch.

Discussion
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[Console] Remove invalid note about empty input options

Fixed in 3.3 (see https://github.com/symfony/symfony/pull/21228/files#diff-8bbcbda2558530b2b02669482549da17R49)

Commits
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c882fe7 [Console] Remove invalid note about empty input options

Author: javiereguiluz

console/input.rst

@@ -261,10 +261,4 @@ Now check the value of the option and keep in mind that ``false !== null``::
     $yell = ($optionValue !== false);
     $yellLouder = ($optionValue === 'louder');
 
-.. caution::
-
-    Due to a PHP limitation, passing an empty string is indistinguishable from
-    not passing any value at all. In ``command --prefix`` and ``command --prefix=''``
-    cases, the value of the ``prefix`` option will be ``null``.
-
 .. _`docopt standard`: http://docopt.org/