[drupal-docs] Documenting PHP requirements

[Karoly Negyesi]

> OPTIONAL REQUIREMENTS
> ---------------------
> - To use XML-based services such as the Blogger API, Jabber, RSS
>    syndication, you will need PHP's XML extension. This extension is
>    enabled by default in standard PHP4 installations.
>
> What about mentioning GD and Mbstring? Are they ever *missing* from PHP4  
> (4.3.3 or greater) or PHP5? Are there other extensions that are really

"These functions are enabled by default, using the bundled expat library.  
You can disable XML support with --disable-xml." so yes, XML is mostly  
there unless your host disabled it.

Debian (and its children) has a separate php4-gd. They even have a  
separate php4-mysql.

So this question needs more documentation, true.

Regards

NK