Clarify what is it whitespace content

git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@332129 c90b9560-bf6c-de11-be94-00142212c4b1
Clarify what normalization is

git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@332130 c90b9560-bf6c-de11-be94-00142212c4b1