Change JDK recommendation

Author: gitseti

CONTRIBUTING.md

@@ -10,16 +10,14 @@ We recommend to develop your changes by using [IntelliJ IDEA](https://www.jetbra
 Therefore, the following guide will focus on creating your changes using IntelliJ. 
 
 Furthermore, the following is needed to make your development efforts as smoothly as possible:
-- A Java 11 JDK (we recommend [temurin](https://adoptium.net/de/temurin/releases/?version=11)) => [Set the JDK in IntelliJ](https://www.jetbrains.com/help/idea/sdk.html)
+- A Java 8 JDK (for example [Azul Zulu JDK](https://www.azul.com/downloads/)) 
 - [Docker](https://www.docker.com/) 
 - Fill out and sign the [Contributor License Agreement](https://www.hivemq.com/downloads/Contributor_License_Agreement.pdf)
   - Send the signed agreement  to ([email protected]) with the subject `CLA for Project: <Project Name>`.
   - Please read this document carefully before signing it and keep a copy for your own records
   - Once we've received your signed CLA, you will be added to the list of contributors and our HiveMQ Development Team will review your contributions
   - In case the rights to all intellectual property created by you are maintained by your employer, including your work on HiveMQ Open Source Projects, you must ensure you have retained all rights to grant the license, or that your employer has agreed to a separate [Corporate CLA](https://www.hivemq.com/downloads/Corporate_Contributor_License_Agreement.pdf)
 
-
-
 ## 1. Setup project
 
 - The following steps will setup a triangle workflow, which will enable you to easily create, update and get your changes into the master branch 
@@ -74,7 +72,6 @@ Furthermore, the following is needed to make your development efforts as smoothl
 
 ![run-config.png](img/run-config.png)
 
-
 ## 6. Commit and Push
 - Before committing execute `./gradlew licenseFormat` to add license headers to each file
 - [Reformat each changed file](https://www.jetbrains.com/help/idea/reformat-and-rearrange-code.html#reformat_file) using the .editorconfig settings of the project