feat: add Dockerfile and update README for Docker setup

[MiguelMedeiros]

@SHAcollision I saw your branch feat/dockerfile after I did my own dockerfile! hahaha 😅

So I've added a few instrucions in the readme and made this PR, feel free to delete it if you think your docker image has a better performance! 🚀

Description

This pull request introduces a Docker setup for the Pkarr server, allowing it to be built and run in a containerized environment. The changes include:

• Dockerfile: Added a multi-stage Dockerfile for building and running the Pkarr server with optimized image size.
• Configuration: The config.toml file is copied to the container for seamless server configuration.
• Documentation: Updated instructions will be provided on how to build and run the Pkarr server using Docker.

Motivation

Containerizing the Pkarr server simplifies deployment and provides a consistent runtime environment. This helps both developers and users by making it easier to run the server locally or in production with minimal setup.

Changes

• Added Dockerfile to the project root.
• Instructions for building and running the server with Docker.

How to Test

Build the Docker image:

docker build -t pkarr-server .

Run the Docker container:

docker run -p 6881:6881 --name pkarr-server-container pkarr-server

Verify the server is accessible at http://localhost:6881.

Checklist

• Added Dockerfile.

• Update README with Docker instructions.

• Ensure the container runs as expected with the default configuration.

Feel free to modify or expand this description to fit any additional details you wish to include.