Update readme and contribution markdown

Actually, my purpose for this project was to create a simple chat application in java without using complex technology. If few of you are interested, we could make this project according to this purpose. I am waiting for your response. @mfiazansari @abyabrkal @NyorJa
- https://opensource.guide/starting-a-project/

- https://gist.github.com/PurpleBooth/109311bb0361f32d87a2

Start with the repository README and the contribution markdown referenced in the issue, then compare their guidance with the linked Open Source Guide and contribution-template example. Confirm the intended project purpose and contribution process before making changes; done means both documents clearly describe how beginners can understand and contribute to the Java chat application.

Written by the indexing model from the issue text.