BUG: Add 'clone --recursive' to the download instructions.
BUG: Add 'clone --recursive' to the download instructions.

Suggested-by: Bill Lorensen <84d2c8570e37200a98386a7f676524f7be88ea5c@gmail.com>

InsightSoftwareConsortium/ITKExamples,InsightSoftwareConsortium/ITKExamples,InsightSoftwareConsortium/ITKExamples,InsightSoftwareConsortium/ITKExamples,InsightSoftwareConsortium/ITKExamples