In KDE4 and before, systemsettings (the KDE Control Center) had a Login Manager entry that you could use to configure KDM. In Plasma 5, there does not appear to be anything that you can use to configure SDDM settings.
I guess systemsettings should recommend sddm-kcm. WDYT?
Indeed it should. It's not very functional at the moment, but it is the correct component.
Fixed on svn
Status: NEW => RESOLVEDResolution: (none) => FIXED