Better documentation for paths

[Martin Kou]

Add more examples and better explanations to these files and variables:

fckconfig.js:

FCKConfig.CustomConfigurationsPath = '' ;
Related to what? Absolute? Domain? Where FCK is?

editor\filemanager\browser\default\connectors\php\config.php:
// Path to user files relative to the document root.
$Config['UserFilesPath'] = '/UserFiles/' ;
Document root? Relative? Absolute? Where FCK is?

$Config['UserFilesAbsolutePath'] = '' ;
This has good comment, but is there any differences if
its empty ('') or commented out?

..Trying to setup FCK's image upload for two days and still it isn't working..