comment: about optional phases

Signed-off-by: Jack Yu <jack.yu@suse.com>

pkg/manager/manager.go

@@ -169,6 +169,7 @@ func (m *SupportBundleManager) runAllPhases(requiredPhases []RunPhase, optionalP
 	for _, phase := range optionalPhases {
 		if err := m.runPhase(phase, &progressCount, maxProgressCount); err != nil {
 			logrus.Errorf("Failed to run optionalPhases %s: %s", phase.Name, err.Error())
+			// Since it's optional, don't return error.
 			continue
 		}
 	}