Fix example to use class constants

Patch by anonymous #46253

git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@334002 c90b9560-bf6c-de11-be94-00142212c4b1
Better variable name in example

Patch by Arjen Schol

git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@334003 c90b9560-bf6c-de11-be94-00142212c4b1
Typofix

Patch by Don Wilson

git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@334004 c90b9560-bf6c-de11-be94-00142212c4b1