Docs: Update getting started with code

[obulat]

Description

• Updates the Getting started with code documentation to make it more accessible to the first-time contributors.
• Replaces 'Development Tools (Node)' section with a 'Prerequisites' section including Node.js, Git and [Optional] Docker.
• Adds a detail about WSL2 that is needed to install Docker on a Windows 10 computer.
• Replaces npm build with npm run dev as a primary command for building Gutenberg: the contributors will probably want to see the changes and debug information when starting out.
• Clarifies that wp-env script sets up the Docker Container and runs it.

How has this been tested?

Run through tutorial and confirm it works as expected

Types of changes

Docs

[github-actions]

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If you want to learn more about WordPress development in general, check out the Core Handbook full of helpful information.

[obulat]

To me it is not very clear what 'Local WordPress Environment setup' is. I have installed WordPress downloaded from wordpress.org before. But 'Local WordPress Environment' sounds like it's something quite different, and I'm not sure what the differences are. So, maybe adding the sentence from below in this section : 'To test (or try out) a WordPress plugin (or Gutenberg WordPress plugin), you need to have WordPress installed' would make it clearer?

[jasmussen]

I would very much appreciate eyes and green checks on this one!

[mkaz]

Thanks for the contribution @obulat 👍
They all look good and add clarity in several areas.