Added manual page to REST Mock (#267)

Reviewed-on: #267
Reviewed-by: Mikolaj Widla <widlam@noreply.example.com>
Co-authored-by: Adam Bem <adam.bem@zoho.eu>
Co-committed-by: Adam Bem <adam.bem@zoho.eu>

Backend/mocked-services/src/main/resources/application.properties

@@ -11,6 +11,6 @@ spring.redis.host=redis
 spring.redis.port=6379
 
 #retention
-retention.minutes-to-delete-message=120
+retention.minutes-to-delete-message=1440
 retention.minutes-to-delete-history-record=1440
 retention.retention-cooldown=1440