Clarify Windows service shutdown behaviour.

@code{mysqladmin}, from the Services utility or by using the

command @code{NET STOP MySQL}.

When running as a service, the operating system will automatically stop

the MySQL service on computer shutdown. In MySQL versions < 3.23.47,

Windows only waited for a few seconds for the shutdown to complete, and

killed the database server process if the time limit was exceeded

(potentially causing problems). For instance, at the next startup the

@code{InnoDB} table handler had to do crash recovery. Starting from

MySQL version 3.23.48, the Windows will wait upto 4 minutes for the

MySQL server shutdown to complete. If you notice that 4 minutes is not

enough for your intallation, it is safest to run the MySQL server not as

a service, but from the Command prompt, and shut it down with

@code{mysqladmin shutdown}.

Please note that when run as a service, @code{mysqld-max-nt}

has no access to a console and so no messages can be seen.

Errors can be checked in @file{c:\mysql\data\mysql.err}.