New documentation pages - need completing

[smilo7]

We have a new documentation structure divided into five main sections. (see #337)

Getting started

Playground

Live Coding

Machine Learning

Language creation

The base files that will be within these sections exist but need filling out. They can be found in /assets/docs/ on the develop branch under the relevant folder names (see sections above).

[frantic0]

@smilo7 I found a component that might be useful for the docs search bar https://github.com/rob-balfre/svelte-select

[smilo7]

@thormagnusson @chriskiefer we can convene about filling out the documentation pages^ here

[smilo7]

All sections now have something in. Major areas that need finishing up (as they currently contain placeholders) are the languages documentation for all languages other than the default language.