Don't have spaces in the project name. It's inconsistent.

This is just for consistency, otherwise we would have to tell it to
look for the qtxmlpatterns/qt-xml-patterns.index file.

Change-Id: Id374511e09bba038209fe48616313b16e0a6e4b3
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>

doc/qt5.qdocconf

 # Name of the project.
-project = Qt Xml Patterns
+project = QtXmlPatterns
 
 # Directories in which to search for files to document and images.
 # By default set to the root directory of the project for sources