Update sourcecode.md

Author: Sunderlandkyl

sourcecode.md

@@ -16,5 +16,7 @@ Plus toolkit contains three main repositories:
 - [PlusLib](https://github.com/PlusToolkit/PlusLib/): Library that contains all data acquisition and processing implementation. It contains a few sipmle tools and test applications but primarily intended to be linked into software applications.
 - [PlusApp](https://github.com/PlusToolkit/PlusApp/): Software applications with graphical user interface that use PlusLib to make features available to end users.
 - [PlusBuild](https://github.com/PlusToolkit/PlusBuild/): Small project that downloads and builds PlusLib, PlusApp and all their dependencies (VTK, ITK, etc.).
+
+Plus toolkit also contains two repositories for storing data and additional documentation:
 - [PlusLibData](https://github.com/PlusToolkit/PlusLibData/): Repository containing config files, sample/test data, and stl files. This includes the files that are installed with Plus.
 - [PlusDoc](https://github.com/PlusToolkit/PlusDoc/): Repository containing additional documentation.