Setup / Get started docs

Description

The current README.md doesn't mention anything regarding how to start the project. It misses some important parts:

Standard commands: npm install and npm run dev, information that npm start refers to a production command (after npm run build for example)
Having the right Node version (at least 20.6) to leverage the --env-file functionality that we are using through tsx
- You can add more information regarding how to load the right node version automatically, for example using fnm that will use the .nvmrc file
Configure the .env file (this will be updated with the issue #6 with more detailed instructions regarding how to setup the database)
Open the browser on the default port (check server.ts to see the right Express port)
Add anything else that you think relevant for new joiners.

It is important that you try to understand what each step do, feel free to ask questions if you have some doubts.

This issue is complementary to #14 as it's more oriented regarding the setup part.