s/ps -aux/ps aux/g, fixes bogus '-' error

re: https://gitorious.org/procps/procps/source/fc7cb8dd4cd91da3d2df35b8863247674e4fd1ed:Documentation/FAQ

> Why does "ps -aux" complain about a bogus '-'?
> According to the POSIX and UNIX standards, the above command asks to
> display all processes with a TTY (generally the commands users are
> running) plus all processes owned by a user named "x". If that user
> doesn't exist, then ps will assume you really meant "ps aux". The
> warning is given to gently break you of a habit that will cause you
> trouble if a user named "x" were created.