Updated documentation

Author: grzegorzswistak

README.md

@@ -14,7 +14,7 @@ Main features are:
 * subscribe and retrieving data from FIFO queues
 
 ## Technologies and libraries
-* Java 17
+* Java 21
 * Spring Web 6.1.4
 * Eclipse Paho Client Mqttv3 1.2.5
 * Jackson Databind 2.16.1
@@ -24,7 +24,7 @@ Main features are:
 ## Requirements
 In order to use the x-connector-library you need to have:
 * **Live Objects account with API key** (API key generation is described in the [user guide](https://liveobjects.orange-business.com/cms/app/uploads/EN_User-guide-Live-Objects-4.pdf#%5B%7B%22num%22%3A190%2C%22gen%22%3A0%7D%2C%7B%22name%22%3A%22XYZ%22%7D%2C68%2C574%2C0%5D)),
-* **Java SE Development Kit 17 installed**
+* **Java SE Development Kit 21 installed**
 * **Apache Maven installed**
 
 ## Build