If you downloaded the source from on-line, this folder will be empty.  You can populate it by downloading the following files from
https://sourceforge.net/project/showfiles.php?group_id=22594

GroboTesting-2-doc.zip
GroboTesting-1-doc.zip
GroboTesting-1.0.0a-doc.zip
GroboTesting-0.9.1-doc.zip
GroboTesting-0.9.2-doc.zip
GroboTesting-doc-0.9.0.zip
GroboUtils-1.0.0a-doc.zip
GroboUtils-doc-0.9.0.zip
GroboUtils-doc-0.9.1a.zip
GroboUtils-doc-0.9.1b.zip
GroboUtils-doc-0.9.1c.zip
GroboUtils-doc-0.9.1d.zip