The TotalPHP site is recommending something that can make your development (and maintenance) life much easier in the long run - using a global configuration file through out your app.
t's one of the basics of PHP and if you read any kind of tutorial or book on the subject it's one of the first things they cover, yet I still see people no using a global 'configuration' or 'include' file. It's one of the easiest things to do and will make your life so much easier! This 'configuration' file will include anything that needs to be run on every page of the website.
They suggest that using this configuration file everywhere (including it over the entire site) can make things easier in the long run. The idea is not without problems, though. It only works until you need something custom for a certain area or page - then you have to hack it to evaluate conditions. For most simple uses, though, its a good way to share information (like database connection details) through out the application.