Updated documentation. Added useful method.

src/main/java/com/github/prominence/openweathermap/api/model/response/DailyForecast.java

@@ -31,6 +31,8 @@ import lombok.EqualsAndHashCode;
 import lombok.Getter;
 import lombok.Setter;
 
+import java.time.Instant;
+import java.util.Date;
 import java.util.List;
 
 @EqualsAndHashCode
@@ -146,6 +148,10 @@ public class DailyForecast implements OpenWeatherResponse {
             return "hPa";
         }
 
+        public Date getDataCalculationDate() {
+            return Date.from(Instant.ofEpochSecond(dataCalculationTime));
+        }
+
         @Override
         public String toString() {
             StringBuilder builder = new StringBuilder();