note 11882 added to function.echo.php

Additional notes to my previous note. "echo" is not a function and will not have value at all. Therefore echo cannot be a valid expression. (In PHP, expression is anything that have value) ?: expects expression. echo() is not a expression, since it does NOT have value. print() is a expression, since it has/returns value. echo() and print() is nearly identical except the fact, that echo() cannot be a expression, as far as I know. [How about add additional comment to manual itself? I think it's worth for it. Editor means "not a function" = "echo does not return value at all" = "not a expression", it was less obvious to me] http://www.php.net/manual/en/function.echo.php