Add missing comma in migration guide example
Add missing comma in migration guide example

Signed-off-by: Patrick Avery <743342299f279e7a8c3ff5eb40671fce3e95f13a@kitware.com>

jbeezley/girder,RafaelPalomar/girder,jbeezley/girder,girder/girder,RafaelPalomar/girder,Kitware/girder,RafaelPalomar/girder,Kitware/girder,jbeezley/girder,girder/girder,manthey/girder,manthey/girder,jbeezley/girder,girder/girder,girder/girder,Kitware/girder,RafaelPalomar/girder,RafaelPalomar/girder,Kitware/girder,manthey/girder,manthey/girder