Add images and refine Getting Started section.

[videlanicolas]

Checklist for this pull request

• I have read the guidelines for contributing.
• I have checked that my code additions did not fail tests.

Description

This merge adds step by step images to better showcase how to install this addon.
Aside from installing it from AssetLib in Godot, the user must add runtime.gd as a singleton.
I'm also re-designing the sections to have them behave with sub-sections.
Since I'm using Visual Studio Code to do my coding, add .vscode to .gitignore, there are no project files to import there.

[ephread]

LGTM!

There's just a lack of padding after the images in the generated documentation, but that's very minor, I don't know how/if it can be solved.

[videlanicolas]

Fixed, I added line separation between those images on my fork PR #3.

[videlanicolas]

Adds to #41 .

[ephread]

@videlanicolas thanks for fixing the spacing issue. I forgot to ask, what's in your .vscode for this project? I use VS Code too on a regular basis and if I don't mind committing a configuration file if it's something that would benefit everybody and enforce some much-needed conventions.

[videlanicolas]

what's in your .vscode for this project?

I use a restructuredText extension, and that has some settings to auto-render the view while working. This is found under .vscode/settings.json. Given that not everybody has this extension, and that the only file under .vscode is this one, I figured we can ignore it since it doesn't break any build.

The contents:

{
    "restructuredtext.confPath": "${workspaceFolder}/docs/source",
    "restructuredtext.builtDocumentationPath": "${workspaceFolder}/docs/build"
}

[ephread]

Alright, makes sense, thanks for the clarification. Merging now!