Improve readme

[Alathreon]

• Improve the general text.
• Explain for the wrapper that running it in local is only usefull if the dev needs to work on it.
• Explain why there are two ways to run the API and parallel to TJ-Bot (+specify why it's important to test both because the API needs to do docker calls from docker).
• Add advised knowledge part at the start mentioning java, gradle, docker and spring.
• Add a diagram for the whole setup and maybe diagrams for the running alternatives.