gin context util + doc fix

pkg/utils/time.go

@@ -9,7 +9,7 @@ type timeUtil interface {
 	// TimeNowUTC Use it everywhere, when you need current time.
 	TimeNowUTC() time.Time
 
-	// DeletedNullTime returns empty sql.NullTime struct.
+	// DeletedNullTime returns empty sql.NullTime struct with valid = false.
 	DeletedNullTime() sql.NullTime
 
 	// NullTimeNowUTC returns valid sql.NullTime struct with current time in UTC.